Inlet-Residue-NGL Solutions for Natural Gas Processing Applications

Oil & Gas Application Note Inlet-Residue-NGL Solutions for Natural Gas Processing Applications To optimize the efficiency and profitability of your ...
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Oil & Gas

Application Note

Inlet-Residue-NGL Solutions for Natural Gas Processing Applications To optimize the efficiency and profitability of your natural gas processing plant you must account for the changing composition of the inlet gas as well as adjust the natural gas liguid (NGL) extraction efficiency to account for marketing conditions. The Inlet-ResidueNGL application for the 700XA gas chromatograph (GC) analyzes the inlet gas and the two product streams in a single field-mounted analyzer to provide real-time feedback to the control system and the operators. Using the live compositions from a single gas chromatograph enables tight control of product specifications thereby maximizing the economic return of the facility.

Figure 1 – The Typical Process Flow of a Natural Gas Processing Facility Showing the Locations of the Sample Points for the Gas Chromatograph Residue (Sales Gas)

Application Overview Natural gas processing involves removing acid gases such as H2S and CO2 and water from the raw inlet gas and then extracting the condensates to produce natural gas, or residue or sales gases, and natural gas liquid (NGL) products. The composition of the inlet gas can vary significantly depending on which well-heads are flowing, the ambient conditions on the primary separators, and the operating state of the gathering network. The composition of the sales gas is constrained by the contract tariffs that typically limit the CO2 and nitrogen levels, the energy content, and the hydrocarbon dew point. The NGL product will have virtually zero CO2 and nitrogen, a small amount of methane, and varying amounts of the heavier hydrocarbons. To maximize the economic performance of your plant, you should be able to quickly adjust to the market prices for the various products that you extract. Typically, if the ethane price is high relative to the natural gas price, the plant will run in ethane recovery mode to produce as much ethane as possible from the NGL stream while filtering out as much methane as possible. If the ethane price is relatively low, the plant will run in “ethane rejection mode” and will produce ethane rich natural gas close to the upper energy and hydrocarbon dew-point pipeline tariffs. Historically, processing plants would run for months at a time in a single mode. However, due to the increasing variability in pricing and demand, plants that can quickly switch between modes can capitalize on short term fluctuations in the market and dramatically improve profitability.

Inlet NGL

The 700XA GPIRN Solution Natural gas processing plants typically have one or two gas chromatographs operating at their facility. We often find that on site plant technicians and engineers do not have the time, training, or expertise to properly operate these complex scientific instruments, therefore increasing the risk of potential lost revenue opportunities or costly shutdowns. The Rosemount Analytical 700XA gas chromatograph configuration for Inlet-Residue-NGL applications or GPIRN for short, is engineered to eliminate complexity and designed to operate remotely and unattended without compromising repeatability. The inlet and residue streams are configured with a wide range of compositions, and the NGL analysis accounts for a wide variation in ethane and propane compositions found between the rejection and recovery modes without the need of operator assistance. See Table 1 for more details. The 700XA’s rugged hardware is designed to increase analytical capability and widens the range of analysis options in a field mounted GC with an ambient temperature rating of -4 to 140 °F (-20° to 60 °C). Whether the analyzer is installed out in the field close to the process or enclosed in a shelter, the 700XA is ideal for natural gas processing applications that require advanced analysis such as C9+ (with hydrocarbon dew point and cricondentherm calculations) or C6+ with H2S.

Oil & Gas Table 1 - Composition Ranges for the 700XA Inlet-ResidueNGL recommended application. Inlet

Sales/Gas Residue

NGL Product








Carbon Dioxide































Hexanes Plus (C6+)

Figure 2– A 700XA Configured for the GPIRN Application that is Suitable for Mounting in a Three-sided Shelter, a GC Cabinet, or an Analyzer House.

System Design The sample system design is critical to the performance of any analyzer system and is an integral component of the Inlet-ResidueNGL application (see Table 1). Particulate filters, liquid filters, check-valves, and bypass flow rotameters are provided for the two vapor streams. Flow switches in the bypass flow can be included as an option. To ensure there is no contamination between the inlet gas and the residue gas sample streams, double-block-and-bleed solenoids are used to select between the calibration and vapor streams. The liquid sample initially is conditioned through a liquid particulate filter with fast bypass loop and armored rotameter mounted externally to the main SHS enclosure. A very low volume side stream is passed into the vaporizing regulator mounted inside the SHS enclosure. The vaporized sample then passes through a manual ball valve that allows for the manual calibration of the liquid analysis. The vaporized liquid sample is injected into the GC oven through a dedicated sample injection valve that is separate from the sample injection valve used for the inlet and residue streams. Both of the sample injection valves vent through dedicated atmospheric referencing valves to enable the purging samples to be routed to a safe sample vent (such as to the flare or vapor recovery system) while enabling the sample loop to be referenced to atmospheric pressure prior to injection into the analytical flow path to ensure accurate and repeatable measurements. All of the vapor state sample handling components are mounted inside a stainless steel heated cabinet that can optionally include a viewing window for easy system checks and can be incorporated into the 700XA gas chromatograph, or mounted remotely.

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Figure 3 – GPIRN Sample System

Oil & Gas

700XA Specifications and Drawings Please consult Rosemount Analytical if your requirements are outside the specifications listed below. Improved performance, other products and material offerings may be available depending on the application.


Environmental temperature: -20° to 60 °C (-4° to 140 °F) Environmental temperature without safety certification: 40° to 60 °C (-40° to 140 °F)

Detector: Thermal conductivity detector (TCD), flame ionization detector (FID), TCD/TCD or TCD/FID dual detector configurations possible; flame photometric detector (FPD) available.

Enclosure Protection Rating: IP66

Gating Options: Fixed-time, slope sensing gating of peaks

• Dimensions (without sample system):

Streams: Up to 20 externally controlled streams or up to 8 internal (includes calibration stream)

• Wall-mount: 711 mm H x 445 mm W x 498 mm D

Chromatograms stored/archived internally: Stores over 80 days of analysis report data and up to 2500 individual chromatograms.

(28'' H x 17.5'' W x 19.6'' D) • Pipe-mount: 711 mm H x 445 mm W x 671 mm D

ƒƒ Standard: 24V DC (21–30V DC)

(60.3'' H x 17.5'' W x 24.1'' D)

ƒƒ Optional: 90–264V AC, 47–63 Hz

Corrosion Protection:

Typical Power Consumption at 22 °C (72 °F): ƒƒ Startup: 105 Watts DC (125 Watts AC) ƒƒ Steady State: 35 Watts DC (40 Watts AC)

• GC Enclosure Material: Copper free aluminum coated with industrial grade powder coat suitable for high humidity and salt- laden environments.

Note: Add 15.5 Watts DC (18 Watts AC) for LOI

• Electronics: All electronic circuit boards are tropicalized with a clear conformal coating.

Communications (Standard)

• Process Wetted Materials: Stainless steel. Where the function of an item excludes the use of stainless steel (e.g. glass rotameter tubes), materials that are resistant to corrosion are used.

ƒƒ ƒƒ ƒƒ ƒƒ

Mounting: Floor-standing (standard), wall- or pipe-mount (optional)


Approximate Weight (without sample system): 50 kg (110 lbs.)


Area Safety Certification Options:* ƒƒ CSA: –– USA and Canada • Class I, Division 1, Groups B, C, and D ƒƒ ATEX / IECEx –– Ex II 2G –– Ex d IIC Gb T6 (Ta = -20 °C to 60 °C)

Ethernet: Two ports – one RJ-45 and one four-wire with 10/100 mbps Analog inputs: Two standard isolated inputs filtered with transient protection, 4–20 mA (user scalable and assignable) Analog outputs: Six isolated outputs, 4–20 mA Digital inputs: Five inputs, user assignable, optically isolated, rated to 30V DC @ 0.5 A Digital outputs: Five user-assignable outputs, Form C and electromechanically isolated, 24V DC Serial: Three termination blocks, configurable as RS-232, RS-422 or RS-485 and one RS-232 D-sub (9-pin) Modbus/PC Connection

Communications (Optional) Two expansion slots available for additional communications. Each slot has the capacity to add one of the following: ƒƒ Four analog inputs (isolated) card

*Stated T-ratings can vary based on applications.

Performance Capabilities

ƒƒ ƒƒ ƒƒ ƒƒ ƒƒ

Four analog outputs (isolated) card Eight digital inputs (isolated) card Five digital outputs (isolated) card One RS-232, RS-422 or RS-485 serial connection card One modem card, 300-19.2k baud

Additionally, a FOUNDATION™ fieldbus module is available. Memory Capacity: 1 GB of flash memory for data storage; 128 MB of SDRAM system memory with 2 MB static RAM (battery-backed)

Carrier Gas: Application-dependent. Typically zero-grade helium, nitrogen, or hydrogen

Carrier Gas Input Pressure Range (recommended): 6.2052–6.8947 bar (90–100 psig)


• Floor-mount: 1532 mm H x 445 mm W x 612 mm D

Sample & Calibration Gas Input Pressure Range: 0.2068–2.0684 bar: 1.0342 bar (recommended) or 15 psig


(28'' H x 17.5'' W x 26.4'' D)

Oven: Airless, maximum 150 °C (302 °F) Valves: Six-port and ten-port diaphragm chromatograph valves. Other types of valves, such as liquid injection or rotary valves, may be used depending on the application

Touch Key Local Operator Interface (Optional) The 700XA local operator interface (LOI) allows for maintenance and operation of a 700XA without a laptop or PC. The LOI is a state-of-the-art high resolution color display that is touch key infrared activated and supports all core GC operations.

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Oil & Gas

Option Selection Use the matrix below to choose the options for your application and build up the model string to order.






700XA Process Gas Chromatograph

Level 1

Hazardous Area Approval

Level 2

Level 3

Level 4

Level 5




CSA rated








W Power AC

Wall-mount Universal 85 to 240V AC

DC 24V DC Front Panel EN Extended switch panel - 18 streams switches and FID ignite button (ignitor not used inless option XX-YY are chosen on level 12) SK Local Operator Interface (LCD) SN Standard switch panel - eight stream switches - not available when an FID option is selected on Level 12 Additional* I/O and Serial/Modem Communications - Slot A

5D 5M 5N 5P 5R 5S 5T

Additional I/O Port - Four Additional Channels of Analog Inputs (Isolated) Additional I/O Port - Eight Additional Channels of Digital Inputs (Isolated) Modem None Additional I/O Port - Four Additional Channels of Analog Outputs (Isolated) Additional Serial Port - (1) RS422 or 485 (Factory/Field configurable) Additional Serial Port - (1) RS232 Additional I/O Port - Five Additional Channels of Digital Outputs (Isolated)

Additional* I/O and Serial/Modem Communications - Slot B 6A Additional I/O Port - Four Additional Channels of Analog Inputs (Isolated) 6D Additional I/O Port - Eight Additional Channels of Digital Inputs (Isolated) 6M Modem 6N None 6P Additional I/O Port - Four Additional Channels of Analog Outputs (Isolated) 6R Additional Serial Port - (1) RS422 or 485 (Factory/Field configurable) 6S Additional Serial Port - (1) RS232 6T Additional I/O Port - Five Additional Channels of Digital Outputs (Isolated)

Level 7

FOUNDATION™ Fieldbus Interface

Level 8

Sample System Mounting Location L Local Sample System - Sample System mounted under GC, with tubing and signaling connections by RAI R Remote Sample Handling System - Includes an external junction box for SHS signal wiring, attached to the 700XA. Signal Wiring and tubing connections are others.

Level 9

Gas Processing Application


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5 GPSCS Level 1



Level 6


Interface Module


Gas Processing - Inlet Residue NGL (three streams)


DeEthanizer Tower Overheads and Bottoms (two streams) Ethane Purity


Propane Purity


Propane Purity Extended (with Propylene)

Level 2 Level 3

Level 4 Level 5 Level 6

Level 7

Level 8








Sample Conditioning System for 700XA - Gas Processing Applications Gas Processing Application SHS type GPIRN Inlet/Residue/NGL GPDET DeEthanizer Tower GPEPS Ethan Purity GPPPS Propane Purity GPPPX Propane Purity Extended (with Propylene) Hazardous Area A Local Sample System C CSA rated components - Class I, Division 1, Groups B, C, D Mounting LS1 Local Sample System - Sample System mounted under GC, with tubing and signaling connections by RAI RS1 Remote Sample Handling Sysem - Includes external junction box, with signal wiring and tubing connection by others. Power A1 110V AC A2 220V AC Window PL Plexiglass - Lexan Vapor Flow Switches V1 Single Vapor Flow Switch V2 Two Vapor Flow Switches V3 Three Vapor Flow Switches V4 Four Vapor Flow Switches Vapor Sample Entry H1 Single Vapor Heat Trace Boot H2 Two Vapor Heat Trace Boots H3 Three Vapor Heat Boots H4 Four Vapor Heat Trace Boots B ⅛ Bulkhead Fittings Liquid Flow Switches L1 Single Liquid Flow Switch L2 Two Liquid Flow Switch L3 Three Liquid Flow Switches L4 Four Liquid Flow Switches

(*) Standard Communications - 5 Di/ 5 DO/2 AI/ 6 AO (All Isolated and (3) RS422, RS422 or RS485 (Factory/Field configurable) serial ports. Optional Accessories Vapor Sample Probe Vapor Sample Probe/Regulator Vaporizing Regulator Heating Sample Probe Liquid Sample Probe Heat Traced Sample Line

Provide line size, process connection details, process pressure and temperature. Provide line size, process connection details, process pressure and temperature. For remote mount at the sample point For vapor samples. To be mounted at the sample point. Provide line size and process connection details. ⅛th Stainless steel heat traced sample tubing including termination kit. Specify length required.

Oil & Gas

Recommended Installation The drawings below represent the minimum recommended installation guidelines for the 700XA Gas Chromatograph. Please consult Rosemount Analytical for detailed installation recommendations for your application.

Figure 4 – GPIRN OD Local

Figure 5 – GPIRN OD Remote

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Oil & Gas

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