AMETEK 241CE II Hydrocarbon Dew Point Analyzer for Natural Gas

Overview

The AMETEK 241CE II Hydrocarbon Dew Point Analyzer, from the Western Research line of AMETEK Process Instruments, gives an accurate and objective direct measurement of the hydrocarbon dew point temperature of natural gas at pipeline or cricondentherm pressure. Natural gas specifications usually include a maximum hydrocarbon dew point, because even small quantities of liquid in transmission lines can damage metering equipment, plug lines, interfere with odorants and, most importantly, create unsafe conditions. The AMETEK 241CE II automates the chilled-mirror method so that the result no longer depends on operator interpretation.

Seven Star LLC supplies the AMETEK 241CE II and its spares to gas producers, gas processing plants, transmission pipeline operators, power stations and industrial gas consumers in Oman and the GCC. We help collect the application data and plan the sample system, and we provide model selection support from Muscat.

How the AMETEK 241CE II Works

The analyzer uses a thermoelectric cooler to control the temperature of a two-surface mirror. The mirror temperature is measured with a platinum resistance temperature detector, which AMETEK notes gives better long-term stability and accuracy than thermocouples. Sensitive optics combined with a precisely controlled cooling rate detect the first formation of condensate, giving improved accuracy and repeatability compared with a manual chilled-mirror device. The single-cell, dual-surface mirror design eliminates interferences and lets the AMETEK 241CE II distinguish between water and hydrocarbon condensate, so the reported value is the true hydrocarbon dew point. A three-stage measurement process requires no tuning, no adjustment and no external coolant; electricity is the only consumable.

Key Benefits

• Direct measurement of hydrocarbon dew point temperature at pipeline or cricondentherm pressure.
• Proprietary three-stage sample filter protecting the analyzer from common natural gas contaminants.
• Unattended operation with low maintenance.
• Digital communications via Modbus RTU and four isolated 4-20 mA outputs.
• Optional remote start of the measuring cycle through an external input.
• Combined package option: can be combined with AMETEK quartz crystal microbalance (QCM) moisture measurement in a single package.

Why Automated Dew Point Measurement

AMETEK explains that automated on-line analyzers are replacing manual chilled mirrors, which need a trained operator, and calculation methods based on gas chromatograph data, which can produce large errors in hydrocarbon dew point because the result is very sensitive to the heaviest components. As general background, a direct measurement such as the AMETEK 241CE II gives operators confidence at custody transfer points and allows faster reaction when upstream dew pointing or gas processing units drift.

Performance and Installation Data

The AMETEK 241CE II methodology is chilled mirror, with an accuracy of ±1°C (±2°F) for hydrocarbon dew point temperature and a sensitivity of ±0.1°C for the temperature measurement itself. Typical flow is 1 to 5 L/min depending on the sample system and pressure, and 1/4 in. stainless steel instrument tubing is recommended for sample transport, with heat tracing where required. Typical ambient temperature is 10 to 40°C or lower depending on the minimum dew point to be measured. Cooling capability is typically 60°C below the temperature at the analyzer installation, so the highest measurable dew point is typically 15°C below the installation temperature; both depend on ambient temperature, gas composition and pressure. Maximum working pressure is 13.79 MPa (2000 psi). In hot climates such as Oman, the installation temperature and shelter design should therefore be reviewed with AMETEK at the application stage.

Electrical and Approvals

The AMETEK 241CE II operates on 120 or 240 VAC ±10 percent, 50 to 60 Hz, with power consumption below 275 W. Outputs are four isolated 4 to 20 mA signals, loop or self-powered. The analyzer measures 571.5 x 838 x 289 mm and weighs 60 kg. Approvals listed by AMETEK include Class I, Division 1, Groups C and D, ATEX/IECEx II 2 G Ex db IIB T4 Gb and CE compliance.

Applications

• Natural gas custody transfer stations.
• Pipelines and underground gas storage.
• Blending control.
• Monitoring superheat in gas turbine feed gas.
• Optimizing switch times for pressure swing adsorption.

The same gas quality station often includes water dew point or moisture analysis, for which AMETEK offers the AMETEK 5100HD TDLAS moisture analyzer, the AMETEK 3050-OLV moisture analyzer and the portable AMETEK 5100P for spot checks.

Sample System Good Practice (General Guidance)

This is general practice rather than AMETEK data. Take the sample from the top of the pipe with a probe that avoids liquids, keep the sample line short, and heat trace the line above the expected dew point to prevent condensation before the analyzer. Reduce pressure only where the measurement procedure allows, because hydrocarbon dew point depends on pressure. Inspect filters on a fixed schedule and keep spare filter elements on site so the AMETEK 241CE II stays in service.

Commissioning and Verification (General Guidance)

This section is general practice rather than AMETEK data. During commissioning, compare the first AMETEK 241CE II results with a careful manual chilled-mirror test or a laboratory analysis of a spot sample collected in a suitable sample cylinder, keeping in mind the different strengths of each method. Agree with the gas buyer or regulator how the analyzer result will be used in the quality certificate, and configure alarms in the control system for dew point limits and analyzer faults. Keep a maintenance log of mirror cleaning, filter changes and verification checks, so the AMETEK 241CE II data can be defended during audits.

Technical Specifications

How to Order

To order the AMETEK 241CE II, send Seven Star LLC the gas composition, line pressure, expected dew point range, installation temperature and area classification. Our Muscat team will coordinate the application review and prepare a formal quotation. The AMETEK data sheet can be downloaded from this page, and we provide model selection support from Muscat for customers across Oman and the GCC.