Systems and methods for the determination of odorants and other sulfur components in natural and liquid gas Axel Semrau GmbH & Co KG Dipl.-Ing. Frank Sasse 1

Topics • Axel Semrau GmbH & CO, the company • Odorization • ODOR handy • ODOR on-line • Field Study 2

The company

• Axel Semrau®, a company of 44 employees, with a technical staff of 34, comprising mostly chemists (PHD) and also some electronic and information technology engineers.

• Since 1973 Axel Semrau as a person later his company is involved in sales and support for analyzers of odorant sulfur compounds 3

Lab for odorization control and gas analysis 4

Axel Semrau GmbH & Co services • Hardware service, repair and maintenance • Supply of calibration gas • Training on site and in the AS training center • Seminars on all topics related to the analysis and monitoring of odorants in gas.

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Odorization • Methane CH4 (major component of natural gas) is without any smell.

• Natural gas is also often without any smell.

• If it smells, that is caused by natural sulfur.

• The concentration of natural sulfur is continuously changing. • For a constant and typical smell an odorant is added.

• Main reason: Everybody should be able to detect (smell) any leak in a house installation.

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• Gas production sometimes strong smell, very high sulfur content (sour gas) • Desulfurization not always necessary • Transport • Odorization • Distribution 7

Odorants • Strong and typical smelling organic sulfur components of the substance classes – Sulfides R-S-R – Mercaptans R-S-H 8

Odorants for natural gas • THT (Tetrahydrothiophen) • TBM (Tertiary butyl mercaptan) • Blends Scentinel® E and Spotleak® 1009 (TBM 75%, IPM 16%, NPM 8% ) Scentinel® TB (50% TBM, 50%THT) 9

Odorants for LPG (liquid gas) • LPG: Propan / Butan • EM Ethylmercaptan • MM Methylmercaptan 10

German Regulation G280 Level of odorant intensity

level definetion

0 not detectable 1 very weak smell 2 weak smell 3 middel 4 strong smell 5 very strong smell 6 maximum

characteristic

threshold limit warning level maximum limit

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German Regulation G280 • Gas should reach a warning smell (level 2) before it reaches a concentration of 20% from LEL (lower explosion limit).

• Similar regulations in other countries 12

Calculation of the minimum odorant concentration in gas • K C = --------------- 20% * LEL mg/m3 (LEL = Lower explosion limit) • Example: TBM in natural gas 0,03 mg/m³ C= ------------------= 3.8 mg/m³ TBM Minimum conc 0,20 * 0,04 entration in Germany 13

Odorization control

Why do we have to check the odor level at all?

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Mechanical problems • Odorant rate is not correct – Bypass odorizer (difficult to adjust) – Injection pump (mechanical failure) – Pump injects only air – Pump is getting no impulse – Remote control broken – Failures caused by operators 15

Chemical and physical problems • Chemical oxidization (especially mercaptans) and adsorption (specially THT) The loss of odorant is depending on the flow and temperature. New PE pipes can also cause a problem.

=>This means you have a big loss of odorant from the point of injection to the households!

e.g: Injection 20mg/m³ THT Concentration at the last point 9mg/m³

=>It is very important to measure the concentration at the end point of the distribution net!

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Measuring methods Smell the gas – Advantage: You smell it!

– Disadvantages: different results from different people – Lower results after several measurement in a short time – Inaccurate – Good as an additional backup.

– In European Countries are not used

any longer

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Measuring methods • Measuring tubes • Advantage: simple to handle, low investment costs • Disadvantage: Many cross sensitivities, Very inaccurate • Due to low accuracy not allowed in

Germany any longer

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ODOR handy 19

ODOR handy • Proofed by extensive testing by many well recognized gas institutes, DVGW institute (Germany Gas Institute) for instance • Proofed by hundreds of companies, using it in daily routine work all over the World eg. (Italy, Spain, France, Poland, Czech Rep., Mexico, Argentina, Brazil, Chile, Bolivia) • Several customers have more than 20 units in use 20

Differences between THT and Mercaptan version ODOR handy TBM • Display 00.1

• Measuring range 0 to 50 mg/m³ • For all mercaptans and

blends with a high mercaptan concentration

• Special version with US units (lbs/MMFC) and

display 0.01 available

ODOR handy THT • Display 000 • Measuring range THT 0 to 100 mg/m³ • For THT and blends with high THT concentration 21

ODOR handy in the field 1. Connect direct to the gas pipe if pressure is 20 mbar (approx. 15 inch of water, 0.5 psi) or with a rotameter if the pressure is higher.

2. Wait just a few minutes 3. Read the result 4. Ready for next measurement after 10 minutes 22

Odorant concentration direct in mg/m³ 23

Operation state • No OFF switch • Sensor should always have voltage • In case of empty battery or new sensor: => let the sensor stabilize up to 12h => then calibrate the ODOR handy 24

ODOR handy • Ex-proof • Can be used everywhere on site • Easily connected to the gas pipe by means of a very short non adsorptive tube • Weight approx. 100g • Selective alarm levels • Simple calibration procedure • Ex-proof battery (6 months continuous work) • Rechargeable battery ex-proof optional 25

Calibration gas set ISO 19739 (ISO 6326 T2) 26

•ODOR handy

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Calibration 1. Battery check 2. Zero point check, adjust if necessary (screw 7) 3. Pure calibration gas pressure regulator 4. Connect calibration gas to ODOR handy 5. Wait till the reading is stable 6. In case of differences: - adjust span/amplification (screw 8) - disconnect calibration gas and wait 10 minutes. - Repeat in case of bigger differences.

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Life time sensor Sensor has to be replaced if: 1. THT: Ce-value is higher 200 TBM: Sensor has not enough sensitivity to adjust during calibration 2. H2S filter is saturated.

• Life time of sensors is about 1-2 years, depending on usage. (Sensors age, even if they are not been used.) 29

ODOR on-line 30

conform to ISO 19739 ( German standard DIN 51 855-07-GC/ASTM D7493-08) • gas chromatographic procedure for online measurement (stationary and mobile) • for more than 30 years successful operating • since 1996 with ODOR on-line systems are always on the latest technical standard • 2010 about 300 instruments on the market 31

Major applications 1. Natural sulfur compounds (e.g H2S, mercaptans) in natural gas – Underground gas storages – Gas power plants – Transmission pipes – Gas quality stations H2S causes corrosion to pipes and turbines 32

Major applications 2.

Odorization control – City gates – Pressure regulation stations – Mobile measurement Odorants fade during transportation!

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Installation • In the field for on-line application • In the lab for manual operation (analyzing of samples) 34

References • E-on Ruhrgas (Germany) • RWE (Germany) • Fluxys (Belgium) • Gas de France • TIGF (France) • Italgas (Italy) • Gas Natural (Spain, Brazil) • Peoples gas (USA) • Kindermorgan (USA) • Polish Oil and Gas Company (Poland) • Société Tunisienne de l’Electricité et du Gaz (Tunisia) • VCP Vychodoceska plynarenska, a.s (Czech Republic) • Igdas (Turkey) • EWE, Bayern Gas …… (Germany) 35

Stationary measurement

On-line measurement in a pressure regulation station

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Stationary measurement

Processing with a special PC Software ODOR

control

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ODOR on-line • Chromatograph designed to fulfill the demands of ISO 19739 (ISO 6326 T2) • packed column • electrochemical detector • 10 ml gas sampling loop 38

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Packed column 40

Heated column 41

Electrochemical detection Explanation of the expression • An electrochemical detector uses the oxidation ability of a substance as its proof.

In the case of H2S and mercaptans the oxidation power of the chrome trioxide is used as the specific proof. 42

Detector 43

Detector tank front view 44

Insulated column and detector tank 45

Reservoir with distillated water for automated refill 46

Manual injection of low pressure samples 47

Injector for manual gas injections 48

Taking samples 49

• Easy to operate • Real-time chromato gram • User defined reports ODOR control Software 50

• Database with all measure ments • Search filters • Export function to Excel™ ODOR control Software 51

ODOR

control

Reportgenerator

User specific reports 52

Data output: 3 x 4-20mA (standard) or Modbus (optional) 53

Option Modbus 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 26.02.2010 16:22:24 --------------- Update of Bus-Memory -------------- File: F:\ODO000005.Results.xml

Parameter: Substance name TBM Value: TBM Type: String Start address: 0 --------------------------------------------------- Parameter: Retention time TBM Value: 94 Type: Single Start address: 10 --------------------------------------------------- Parameter: Peak area TBM Value: 409305 Type: Int32 Start address: 20 --------------------------------------------------- Parameter: Concentration TBM Value: 2.8

Type: Single Start address: 30 • All results with name of the substances, retention time, areas and … • Groups of substances • 8 different alarms • Status of the instrument • Information about the last run 54

THT in natural gas 55

THT and TBM in natural gas 56

Natural Sulfur and THT 57

complex mercaptan blends 58

Elution sequence of odorants

Name Hydrogen sulfide Methylmercaptan Chemical formula H2S CH3SH Ethylmercaptan Isopropylmercaptan C2H5SH C3H7SH Tertiärbutylmercaptan (CH3)3CSH n-Propylmercaptan sek.Butylmercaptan n-Butylmercaptan THT C3H7SH C4H9SH C4H9SH C4H8S Retention time 0,5 1,0 1,3 2,7 4,0 4,8 9,3 11,7 35

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Odor on-line • Measuring range – THT 0.1 mg/m³ - about 100 mg/m³ – H2S 0.1 mg/m³ - about 100 mg/m³ – Mercaptans 0.01 mg/m³ - about 100 mg/m³ • Carrier gas – Nitrogen or compressed oil free air • Automatic and manual injector 60

Advantages of the electrochemical detector • The detector is not sensitive to other compounds in natural gas • Low detection limits 0.1 mg/m³ • Linear within the normal measuring range • Extremely robust and stable in on-line applications 61

Mobile measurement •

12 V use

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Heated column

•

No cross sensitivities

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Option: Electronically flow controller

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electrochemical detector Detec tor feed CrO3 solution operation position 1 c m park / transport position 63

Mobile sampling •

No sample transport.

•

Connect the instrument direct to the gas pipe

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Service company: Schütz 65

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measureing point 68

Measureing point

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Comparission ODOR handy / ODOR on-line 71

Total Sulfur a) 1 ODOR on-line For H2S, natural mercaptans (and odorant) b) 2 ODOR on-lines One for H2S, natural mercaptans (and odorant) One for Carbonylsulfid (COS) c) ODOR on-line plus ODOR total S II 72

Total Sulfur a) 1 ODOR on-line For H2S, natural mercaptans (and odorant) Project with RMG Container for BTU and sulfur measurement 73

Total Sulfur b.) 2 ODOR on-lines One for H2S, natural mercaptans (and odorant) One for Carbonylsulfid (COS) 74

Total Sulfur c.) ODOR on-line plus ODOR total S II 75

ODOR total S II 76

Field study Gas distribution net from Mark E • Length: 563 km • Sales volume: 2.300 Mio. kWh • customers: 48.000

• City and area of Hagen Stand December 2002 77

Measuring methods 1. Stationary on-line measurement 2. Mobile measurement with a car 3. On demand: quick check with an ODOR handy 78

Sample sites 79

1. Stationary on-line measurement • Data transmission to the central control station 80

2. Mobile measurement with a car • factory • Public building (school) • Small pressure regulation station • Sampling point on the street 81

Summary field study Mark E Optimum control procedure for odorization level by: • On-line measurement (24h) ODOR on-line • Good positioning of sample sites • Flexible through a mobile gas chromatograph • Quick results from new sites with the handheld instrument (ODOR handy) 82