Process Analysers For Gas and Liquid Phase
Moisture technologies and their ranges No single technology can cover the entire range All have limitations TDL Quartz Sensors Chilled Mirror Hygrometer Impedance Dew-Point Sensors RH Sensors -110-100 -80-60 -40-20 0 +20 +40 +60 +80 +100 Dew Point o C 10ppb V 10ppm V 1000pp 23000ppm V 20 % V/V >50 % V/V m V
Promet I.S. User interface Control Unit Sensor Assemblies Optional pressure transmitter Built-in I.S. barriers Sensor block Electrical connections Dew-point transmitter Power port and switch Safe area Hazardous area
Promet IS Process analysers and sample systems Promet Sampling System Easidew II IS
A real example of diurnal heating PROCESS
Promet EExd: Flameproof Certified Purpose designed flameproof EExd process moisture analyser Totally hazardous area installed analyser ATEX certified IEC Zone 1 & 2 NEC Class 1, Div 1 & 2
Promet EExd Measurement capabilities Single- or dual-channel Comprehensive moisture content units: ppmv/ppbv, mg/nm3 and LB/MMSCF, for ideal and natural gas Pressure compensated automatic unit-tounit conversions for both moisture content and dew point Natural gas data using IGT#8 or ISO18453
Conversion from measured dew point to moisture content Moisture Content, mg/m 3 200 180 160 140 120 100 80 60 40 20 0 Moisture content in gases @ 7MPa pressure Natural Gas Air n Ideal Gas -35-30 -25-20 -15-10 -5 0 5 10 Temperature, o C
Quartz Crystal Quartz Disk Diameter: 15,5mm Quartz Disk Thickness: 0,1665mm Moisture adsorbs or desorbs on polymer layer Causes a change in mass of the vibrating crystal Increase in mass reduces frequency, a decrease has opposite effect Sorption process fully reversible No long term drift Reliable and repeatable performance
Calibration curve for QMA PROCESS
Internal Sampling System Mechanical Assembly Internal sampling system is selfcontained in the oven: Fan Heater (11W) T probe (±0.1 C stability) Flow meter (sensor cell outlet) Sensor block Note: Internal drier is external to the oven to retain full efficiency
Measurement Circuit PROCESS
Intuitive touch screen Easy access to functional parameters Front Screen Secondary Screen
QMA2020 Typical Response PROCESS
Michell s Quartz Crystal QMA 2020 Series Eexd Zone 1 0.1 500 ppmv, trend to 1000ppmV On line verification ± 10% reading accuracy -20 to +60 C ambient conditions Selectable 0-1v, 4-20mA (2of), RS485 serial communications
TDL 600 Basic Theory Works in NIR region Gas molecules vibrate at specific frequencies If infrared energy passes through gas some energy gets absorbed Water has two different atoms so resonant IR absorption will happen N2 has two identical atoms it is not IR active Water in complex and non linear Has 3 modes of vibration Locations of peaks unique to water Allows water to be detected avoiding interference from other gases
TDL Basic Theory To avoid just being a molecule counter gas is passed into a sample cell with mirrors to increase the path length.
Basic Theory Direct Absorption Spectroscopy Wavelength Modulation Spectroscopy Direct absorption: simpler but least sensitive WMS sharper and less temperature dependant
TDL600 Highlights 1-5000ppmV range ± 1% reading of 1 ppmv Local display EExd rated IEC and ATEX rated ppmv, lb/mmscf, mg/m3, C dp 4-20mA (x3) and MODBUS RTU outputs 5000 point data logger Fast response to both increase & decrease in moisture Active Background Compensation Long term calibration free operation
LIQUIDEW IS & EExd Moisture in Liquid Analyzer Complete moisture measurement packages for critical petrochemical liquid applications
Moisture Measurement in Liquids Liquids consisting of non polar molecules such as hydrocarbon chain or hydrocarbon rings do not mix with water (immiscible). Liquid Hydrocarbons can absorb a certain amount of water vapour (dissolved moisture) and thus have a limited saturation concentration. Dissolved moisture acts as a gas, exerting a partial pressure with corresponding dew point temperature. Saturation concentration is specific to the liquid and highly dependant on temperature.
Henry s Law In chemistry, Henry's law is one of the gas laws. It was formulated by William Henry (1774-1836) of Manchester, England in 1803. Henry s Law states that: At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
Henry s Law Henry s Law is used for determining Weight Portion of moisture in total Liquid. Moisture content in ppm W = K X P w where K is Henry s constant of particular solute liquid at measured temperature, P W is Partial water vapour pressure, measured by our ceramic moisture sensor. K = C S /P S where C S = Saturation Concentration in ppm W and P S = Saturation vapour pressure at temperature of measurement.
Solubility data Cs, ppmw 700 600 500 400 300 200 100 0 Saturation concentration of propane and butane 0 10 20 30 40 50 Temperature of liquid, deg. C Propane Butane
Solubility data for mixtures Cs, ppmw 700 600 500 400 300 200 100 0 Calculated saturation concentration of typical LPG propane and butane mixtures 0 10 20 30 40 50 Temperature of liquid, deg. C Propane Butane 70%C3-30%C4 80%C3-20%C4 90%C3-10%C4
Liquidew IS Moisture in liquid analyzer with remote intrinsically safe measurement transmitters
Liquidew IS Sampling Systems PROCESS
Liquidew EExd: Flameproof certified Purpose designed flameproof EExd process moisture analyser Totally hazardous area installed analyser ATEX & CSA(US) certified IEC Zone 1 & 2 NEC Class 1, Div 1 & 2
Liquidew EExd Measurement capabilities Single- or dual-channel Automatic real-time Henry s Law calculation of moisture content Factory programmed saturation concentration values for 6 common solutes Custom Cs data entry for other solutes and mixtures
Standard sample systems PROCESS
CONDUMAX II Hydrocarbon Dew Point Measurement The latest generation Hydrocarbon dew point analyser from Michell Instruments offers a major step forward in the precise measurement and control of a vital natural gas quality parameter.
WHAT IS HYDROCARBON DEW POINT? THEORECTICAL DEFINITION: ISO 14532:2005 (Natural gas Vocabulary) defines hydrocarbon dew point as The temperature above which no detectable condensation of hydrocarbons occurs at a specified pressure. APPLIED DEFINITION: Hydrocarbon Dew Point is the temperature at which the first visible film of hydrocarbon condensates are observed when natural gas is cooled, at constant pressure. Typical Phase Envelope for Northern Europe natural gas Pressure MPa 8 7 6 5 4 3 2 1 Water and HC liquids preset in gas HC liquids present in gas H 2 O Dewpoint Wholly gaseous HC Dewpoint 0-40 -30-20 -10 0 +10 Temperature, C
EASEE-gas approved gas quality parameters and values Parameter Unit Min Max Recommended implementation date WI kwh/m 3 [13.60] 15.81 1/10/2010 d m 3 /m 3 0.555 0.700 1/10/2010 Total S mg/m 3-30 1/10/2006 H 2 S + COS (as S) mg/m 3-5 1/10/2006 RSH (as S) mg/m 3-6 1/10/2006 O 2 mol % - [0.01]* 1/10/2010 CO 2 mol % - 2.5 1/10/2006 H 2 O DP o C at 70 bar (a) - - 8 1/10/2006 Some exceptions HC DP o C at 1 70 bar (a) - - 2 1/10/2006 EASEE-gas: European Association for the Streamlining of Energy Exchange Objectives to harmonise business practices across the industry 80 cross border points across Europe
Hydrate formations PROCESS
Compressor damage PROCESS
HC Dew Point Applications Hydrocarbon Dew Point Reduction Processing
Hydrocarbon Dew point Reduction Plant PROCESS Water dew point reduction Hydrocarbon Dewpoint reduction Well Head 10-15MPa Glycol Contactor Separator NGL P = 3 to 5 MPa J.T. Valve L.T.S. Condensate Transmission Pipeline 7 to 15 MPa Compressor After extraction from the gas field, natural gas is processed to remove water and heavy hydrocarbon components, before transmission through the pipeline network. This diagram shows a typical plant for the removal of both excess moisture and heavy hydrocarbons
What the processing achieves Adds cost to the process in running equipment Loss of NGL s = Loss of burn value
HC Dew Point Applications Gas quality measurement at custody transfer
HC Dew Point Applications: Gas Turbine Electricity Generation Avoid liquids in hot gas path Avoid flashbacks Turbine manufacturers stipulate 20 to 30 C of superheat for fuel gas to low NOx plant Dew-point measurement enables control of fuel gas heaters Potential return on investment through reduced parasitic load
How can hydrocarbon dew point be measured?
Manual Visual Cooled-Mirror Dew-Point Checker
Images courtesy Ametek PROCESS
Equation of State Method Using GC Analysis Gas Chromatographs provide Heating/Calorific Value (BTU/CV) Fiscal metering is based on BTU/CV and thus there is a large installed base Field units are mainly C 6 + with a few C 9 + Equations of State (EOS) can give a calculated HCDP
ISO 23874 (2006) Natural Gas Gas Chromatographic requirements for hydrocarbon dew point calculation be capable of measuring alkenes up to and including dodecane, be capable of measuring individual alkenes at a concentration of 0.000 000 1 (0.1 ppm) be capable of measuring individual alkenes at a concentration of 0.000 000 1 (0.1 ppm) measure all hydrocarbons in the range C5 to C12
Equation of state calculation from extended GC analysis: Sample, analyse, calculate PROCESS Mol% C 1 Methane CH 4 88 C 2 Ethane C 2 H 6 5 C 3 Propane C 3 H 8 2 C 4 Butane C 4 H 12 1 C 5 Pentane C 5 H 14 0.3 C 6 Hexane C 6 H 16 0.1 C 7 Heptane C 7 H 16 0.03 C 8 Octane C 8 H 18 0.01 C 9 Nonane C 9 H 20 0.001 C 10 Decane C 10 H 22 0.0003 C 11 Undecane C 11 H 24 0.0000 C 12 Dodecane C 12 H 26 0.0000 CO 2 1.5 H 2 O 0.005 (50ppm) H 2 S 0.0001 N 2 2.0 O 2 0.08
3 calculations 3 results PROCESS
C6+ dew point behavior -12ºC 45 B 10º C 35 B 45º C 38 B 76º C 32 B If C9 changes by 1ppm HCDP would change by about 0.5ºC. However: If C7 changes by 8ppm HCDP would change by about 0.5ºC Source: AN ANALYSIS AND PREDICTION OF HYDROCARBON DEW POINTS ANDLIQUIDS IN GAS TRANSMISSION LINES
The DARK SPOT Technique Light Source Detector Light Source Detector Dry Wetted with Condensate
The DARK SPOT Technique PROCESS - - - - - - - The dark spot forming
Signal Change, mv Signal Change, mv PROCESS CONDUMAX Hydrocarbon Dewpoint Analyser 1500 Confronting the issues: High sensitivity - DARK SPOT Technique Facility to produce an LGR plot - sensitivity calibration routine Decoupling the sample flow rate/cooling rate interrelationship - fixed volume sample analysis 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 Trip point setting at 275mV (Factory Default) 10 15 20 25 30 35 40 45 50 Optical Surface Temperature, deg.f Optical Surface Temperature, F
CONDUMAX II Hydrocarbon Dewpoint Analyser Automatic System Dark Spot HCDP measurement Optional Ceramic Moisture Sensor EEx d ATEX approval Automatic, low maintenance
CONDUMAX II Hydrocarbon Dewpoint Analyser Sampling System Sensor Assembly Remote interface Control Unit
Inside the optical sensor cell PROCESS
Condumax II Optional moisture measurement Displays in C and mg/m3 Michell Ceramic Moisture Sensor Line pressure transducer Accuracy +/- 1 C WDP 300 barg rated Sour gas compatible
Thanks for you attention and patience Questions??