Recent Improvements in Process GC Instrumentation

Transcription

1 ISA Houston, TX Oct., Recent Improvements in Process GC Instrumentation Dr. Jack Driscoll PID Analyzers, LLC copyright PID

2 Presentation Objectives A new Process GC has been developed with the following characteristics: Compact 19 rack/wall mount PC based with Windows operating system PeakWorks chromatography software Simple interface & ease of of use State-of-the-art I/O Improved detector performance Additional interface devices for numerous applications: concentrator, sparger

3 Selected Applications for PGC ppb Levels of BTX in beverage grade CO2 Detection of VOCs under Texas Chapter 115 Sparging/Headspace System for On-line Analysis of Total or Speciated VOCs in Water

4 What are the improvements? More compact size- 19 rack mount PC rather than up USB port for control/upgrading Color VGA display Mouse operated Software Easy to change or modify program Detectors- new & improved More outputs Easier to expand features More digital I/O

5 MicroProcessor vs PC Speed vs 750 MHz, 100 MHz bus Memory 256 MByte Ram Data Storage 40 GByte Plug & Play Windows, C++, Multitasking Outputs: 4-20, RS232, network card (10/100)- easy to network USB peripherals Color VGA Display

6 up PC Speed varys 750 MHz, 100 MHz Bus Memory Plug & Play Windows MT Operating Sys Network Cap. USB Peripherals varys No No Special No No 40 Gbyte HD Yes Yes Windows Yes floppy, USB Disk

7 Model 301-B mouse USB Port

8 PID 10.2 ev On-screen keyboard Method

9 Rear View of Model 301-B PC Relays Fluidics I/O

10 Top View 301-B Oven PID Dual PCB electronics

11 GC Signal Schematic ADC 16 bit AMP Detector Keyboard Display Diagnostics PC DAC to ma RS232 Digital I/O Alarms Digital I/O- valves Time clock, data calc & storage on hard drive

12 301-B B GC Fluidics

13 Calibration

14 PID 10.2 ev- 3 ppb Detector Parameters

15 Troubleshooting/Remote Voltage outputs for 2 detectors (A & B) displayed on bottom of screen, temperature, mode (sampling, inject, equilibrate, analyze, alarm) & diagnostics- oven T, bad cal, A/D board, Separate diagnostics alarm Remote operation- 301-B can be controlled by PLC- Run, Cal., Ready via a TTL signal

16 Optimization Parameters for Auto GC s Pre column- to remove heavies, polar or non polar species, protect analytical column Inject time- can be varied to remove heavier species Detector- Selectivity- HNU has 6 detectors to choose from;pid lamp energy can be varied Packed and capillary columns can be mixed Backflushing to remove heavies; foreflushing to remove light compounds, heart cutting to remove a compound during the run Pressure programming- new option for 2004

17 301-B B Continuous Monitoring GC Analytical Column Mode for Specific Detection Six detectors to choose from: Specific to Universal Minimum Maintainance Data Processing of Concentrations X (Div. 1) or Z purge (Div. 2) Outdoor Locations-

18 GC Detectors PID- hydrocarbons (>C 4 ), inorganic species H 2 S, NH 3, PH 3, etc. at ppb to ppm levels (ppb-%) FID- specific for hydrocarbons (ppm-%) FPD- specific for S or P (ppb) ECD- specific for chlorinated HC or nitro compounds (ppb) FUV- nearly universal detector (ppb to%) TCD- universal detector ( ppm to %)

19 Most Sensitive Detectors for VOC s Photoionization Detector 1 st commercial introduction in 1976 by HNU (Driscoll)- 50x more sensitive than FID for aromatics- low ppb Far UV Detector 1 st commercial introduction in 1985 by HNU (Driscoll)-low ppm sensitivity- nearly universal Flame Ionization Detector 1 st commercial introduction in late 1950shydrocarbons- sub ppm

20 What Improvements have been Made to the GC Detectors PID Mechanical, chromatographic, electronic & software-results: improved detection limits from 2 ppb to < 0.5 ppb FUV Electronic, chromatographic, & software-results: improved detetion limits from 1-2 ppm to ppb FID Electronic, chromatographic, & software-results: from 100 ppb to ppb

21 hν Photoionization Detector Process R + hν = R + + e - where R= molecule hν = a photon with an energy > IP of R R + = positive ion e - = electron

22 PID Characteristics Linear dynamic range > 5 x10 7 Detection limit <0.5 ppb benzene Non destructive; other detectors can be run in-series Sensitivity increases as the carbon number increases (carbon counter) For 10.2 ev lamp, responds to carbon aliphatic compounds > C 4, all olefins and all aromatics The PID also responds to inorganic compounds such as H 2 S, NH 3, Br 2, I 2, PH 3, AsH 3, e.g. any compound with an ionization potential of < 10.6 ev The PID is more sensitive than the FID; >200 x more sensitive for aromatics, 80 times for olefins, & 30 times for alkanes > C 6 Non destructive detector; other detectors can be run downstream Concentration sensitive detector

23 Far UV Absorbance Detector

24 FUV Characteristics Measures 124 nm-log signal Nearly Universal Response Linear (Log) Range > 10 5 Low dead volume < 40 ul- fast response Non- destructive Environmental applications: freons, landfill gases, O 2, CO 2, CH 4 at same detection limit as FID (0.1 ppm), VOCs

25 Flame Ionization Detector hν

26 hν FID characteristics Linear dynamic range > 2 x 10 6 Detection limit 50 ppb Sensitivity increases as the carbon number increases (carbon counter) Sensitivity to substituted species depends on the mass of carbon present and the ability to break the carbon bonds The FID is most sensitive to hydrocarbons Detector is destructive since sample is burned Requires the use of zero grade (high purity) hydrogen and air to produce the flame

27 Detectors and Characteristics PID FUV FID Species C1-C4 C4 alkanes N Y Y C5+ alkanes Y Y Y Alkenes Y Y Y Aromatics Y Y Y Dynamic Range 5 x 10exp7 1 x 10exp5 1 x 10exp6 Detection Limits Air aromatics < 0.5 ppb ppb ppb alkenes <5 ppb ppb ppb alkanes < 10 ppb ppb ppb Water aromatics < 0.1 ppb ppb ppb alkenes 0.1 ppb ppb ppb alkanes 1 ppb ppb ppb

28 Compounds Measured under TCEQ Chapter 15 Photochemically active compounds: Ethylene Propylene 1,3 butadiene C4 alkenes

29 PID 10.2 ev 3 ppb BTX

30 PID 10.2 ev 5 ppb BTX

31 CO in stack gas FID with methanizer CH4 24 ppm CO

32 Types of GC Columns The 301 B can have packed or capillary columns (0.3 or 0.32 mm) Typical cap column 30M x 0.53 or 0.32mm We use PLOT for inorganic, fixed gases or light hydrocarbons One or two columns packed or capillary

33 PID Analyzers 301 B Features Multipoint Sequencer- 1, 4, 8 points Six detectors to choose from specific to universal Analytical Column Mode for Specific Detection Pre column to remove interferences & protect analytical column Built in Diagnostics Long term reliability Data Processing of Concentrations (1 Y storage) X or Z purge- not necessary- in control room Windows 2000 operating system PeakWorks Chromatography Software VGA color display Mouse (left & right buttons) On screen keyboard USB Port for accessories

34 Features (continued) Model 301-B B GC Standard Features Single sample stream; autocalibration Single or dual detector capability, single or dual columns, Outputs- 0-1V, RS232 (2), plus alarms (lo, high), 4-20 ma (optional), LAN 40 GByte hard drive for data storage VGA Color flat panel display, ASCII keyboard Automatic report generation Extensive diagnostics

35 Additional Capabilities of the 301 B The 301-B has a 16 channel ADC Six are used for the 301-B There are 10 additional channels for sensor input Sensors available are: Electrochemical, IR, UV, Semiconductor for more than 20 different species

36 Up to 10 sensors Keyboard Display Diagnostics Optional Input Signals ADC 16 bit PC AMP DAC to ma RS232 GCDetector Digital I/O Alarms Digital I/O- valves Time clock, data calc & storage on hard drive

37 Concerns to be Addressed by Real-Time Monitoring/ Leak Detection System Local/Federal Agencies Reporting Package Worker Protection & Long term issuesinsurance Neighbors around the plant/site Rapid leak Detection GC System- Uptime Integration into their data collection system Maintenance/Service contracts

38 Summary The 301-B is a compact 19 rack mount GC The instrument is PC based with considerable expansion capability including LAN, RF modem, USB and additional (IR, electrochemical) sensors There are 3 detectors for VOC measurement with ppb capability: PID, FUV& FID The GC is useful for measurements of photochemically active olefins from at ppb levels in water It is ideal for the State of Texas Chapter 115