Show Preview - PEFTEC 2017 A specifi c product in the MEDOR® range named energyMEDOR®


allows the speciation and measurement of sulfur compounds in different matrix (natural gas, LPG…). The equipment specifi cations are given here:


The energyMEDOR® is capable of analysing individual Sulphur


compounds and Total Sulfur with direct measurement. In addition the internal calibration stream (permeation tube installed into the instrument) is analysed at the end of every analysis, at a very low concentration level (ppb or ppm). Results are thus automatically validated. No external calibration cylinders are required for operation and calibration. The energyMEDOR®


can detect Total


Sulphur compounds thanks to its Sulphur Specifi c Detector (SSD). A list of possible sulphur compounds to measure is given below: 1. Hydrogen sulphide (H2


S)


2. Methyl Mercaptan 3. Ethyl Mercaptan 4. N Propyl Mercaptan 5. Iso Propyl Mercaptan 6. Tertiary Butyl Mercaptan 7. TetraHydroThiophene (THT) 8. Total Mercaptans (as sum of 2+3+4+5+6) 9. Total Sulphur (as sum of 1+2+3+4+5+6+7)


Every component and the sum of them can be transferred to a data logger through a specifi c communication protocol (e.g. Modbus, 4-20mA outputs…).


To operate, the instrument specifi cations are: • Gas supply: N2


or zero air • energyMedor® can be installed either in 19’’ rack or in an ATEX Cabinet type “p” or “d”.


An industrial computer is located inside the enclosure and has an internal mouse and keyboard available in case local maintenance is required. The computer transmits data to a local central room via RS-485 or via an Ethernet connection. In cases of long distances between the instruments and the local central room, the network connection can be routed via RS-485. Data can be sent by the computer either via 4-20 mA output or Modbus RTU protocol.


Thanks to this internal PC, it is possible to collect data with Vistachrom software. The software permits the transference of concentrations, Total Organic Sulfur (TOS) calculations and status (calibrations, streams, default analyser) via the Modbus protocol to the control room.


A calculation module is available and has the capacity to perform concentration daily averages (on 24 hours) on selected components.


The Odourisation of natural gas is an important application for which the energyMEDOR®


is a key product.


For safety reason, natural gas is required to be readily detected by a person with a normal sense of smell. Therefore, the MEDOR® solution needs to be as sensitive as the human nose.


To demonstrate its sensitivity, some performance tests have been carried out. Analysis of 8 Sulphur compounds from external certifi ed standards have been performed. Below are shown the results obtained for the stability tests and linearity tests after 20 consecutive analysis were executed on the following components:


Table 1: List of molecules analyzed during the test Figure 1: Typical chromatogram obtained with energyMEDOR Hydrogen sulphide


Methyl Mercaptan (MM or MTM) Ethyl Mercaptan (EM or ETM) Dimethyl Sulphide (DMS)


(iso) 2-Propyl Mercaptan (IPM) ter Butyl Mercaptan (TBM) (N) 1-Propyl Mercaptan (NPM) TetraHydroThiophene (THT)


H2 S


CH3 CH3 CH3 (CH3 (CH3 CH3 C4


-SH CH2


-SH


-S-CH3 )2 )3


H8


CH2 S


-CH-SH -C-SH


CH2 -SH Table 2: Concentrations obtained for H2 S, MM, EM, IPM, TBM, THT and DMS STD over 20 measurements H2


Mean SD


Relative Error (%) Repeatability (%)


Reference concentration


S 3,16


0,011 1,50 0,72


3,11 (+/-4%)


MM 9,06


0,031 0,84 0,68


9,14 (+/-4%)


EM 6,02


0,072 0,21 2,38


6,01 (+/-4%)


Table 2 (above) summarises the different results obtained by compound. Table 3 represents the criteria for compliance with the ISO 19739 norm and the obtained values using the energyMEDOR® Repeatability (%) H2 S


MTM (or MM) ETM (or EM) IPM


TBM THT


Performance criteria 3 2 4


10 7 4


An example of a chromatogram obtained with the energyMEDOR®


shown in Figure 1 below.


At the end of each chromatogram, a validation of results is carried out by injecting and analysing the DMS from the internal calibration device certifi ed (permeation tube).


Another application for the natural gas market is related to Integrity Monitoring. During the extraction of raw natural gas and following processing, midstream companies are required to track the level of H2


S and TS (Total Sulphur = H2 S + Total


Organic Sulphur (TOS)). If the concentration measured exceeds the required level, the midstream companies must shut down the


Obtained value 0,72 0,68 2,38 1,20 1,21 1,07


for the measurement of H2S at around 1mg/m3 is instrument. Relative reproducibility (%)


Performance criteria 25 10 30 20 25 20


Obtained value 1,50 0,84 0,21 2,06 0,96 0,51


gathering line until the measurements are displaying the required concentration levels again.


For these analysis, the sample is fi rst loaded into a loop and then injected in an analytical column to separate H2


S from the other


Sulphur compounds (shown in Figure 2). To expand the applications of the MEDOR®


module has recently been developed by Chromatotec®


, a specifi c sampling . It can


inject extremely low volumes (from 0.1 to 1 µL) into MEDOR® autoGC for LPG analysis (Propane and butane), which is directly connected in the sampling module inlet. It is then vapourised and injected into the MEDOR®


directly. Other applications for heavier liquid hydrocarbons, like condensate or gasoline, are


Concentration (mg/m3 IPM


8,05


0,048 2,06 1,20


8,22 (+/-4%)


)


TBM 5,18


0,031 0,96 1,21


5,13 (+/-4%)


THT


27,20 0,146 0,51 1,07


27,06 (+/-4%)


DMS STD 6,04


0,021 0,19 0,71 6,03


(+/-10%)


37


All tests performed are part of a protocol document pertaining to analyser validation and are defi ned by a European third party laboratory. To validate the instrument, it is required to perform 20 analysis and to obtain results in compliance with ISO 5725-2. The samples are generated from different standards.


The relative reproducibility and repeatability values are much better than performance criteria values as defi ned in the ISO 19739 norm. All tested compounds have a linear response (to SSD) in the trial conditions (i.e. range of 0 – 5 mg/m3 most Sulphur compounds and THT range 0-25 mg/m3 R2


for ) with a


> 0.995 for all compounds. So the conclusion was that the performance criteria are in compliance with the norm.


Figure 2: Analysis of H2 S, TOS and TS in two minutes


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