Leak detector recognises ultrasound 'fingerprints'

Paul Boughton

Accurate gas sensing is a crucial feature of plant health and safety regimes - and also for the efficient and reliable operation of oil and gas plants. Eugene McCarthy reports.

Designed to withstand the harshest environments, from arctic to tropical conditions, the new FlexSonic acoustic gas leak detector (Fig.1) from Det-Tronics is described the company as a revolutionary step forward over traditional gas leak detectors. "It's the first non-contact gas leak detector of its kind that recognises unique ultrasound 'fingerprints,'" said md Jerry Slocum.

The detector analyses 24 discrete ultrasonic bands, ignoring nuisance ultrasonic sources. A high-fidelity microphone continuously monitors for the distinct ultrasound emitted by pressurised gas leaks across the widest spectrum of frequencies.

Unlike traditional non-contact gas leak detectors, the FlexSonic detector can be programmed to ignore background noises, discerning between gas leaks and environmental noises such as metal-on-metal contact, fans, machinery or vehicles. For noisy applications, it learns both regularly occurring and random sounds, detecting the actual acoustic gas leak 'signature'.

"This next-generation technology improves gas leak detection capabilities by recognising real leaks and reducing false positives," said Michael Bragg, product group manager, Det-Tronics. "For potentially hazardous locations, the FlexSonic detector offers an additional layer of protection that complements traditional gas leak detectors."

The company has also announced that its X3302 multi spectrum infra red (IR) hydrogen flame detector is certified as SIL2 capable by Exida. As a result it now can be used in extreme hazard applications that pose a high risk of hydrogen fire, including refineries, chemical loading, compressor areas, and gas plants.

For its part, Emerson Process Management has released the Micro Motion gas density meter, the next generation of the Micro Motion 7812 gas density meter designed for natural gas custody transfer, refinery/fuel gas measurement, hydrogen purity monitoring and many other process gas applications.

In applications where the ultimate in real-world measurement performance is required, the Micro Motion gas density meter is the ideal choice to solve problems that users confront on a daily basis such as reducing custody transfer gain/loss errors, inefficient hydrogen cooling of turbines or reduced steam heat and reliability from fired heaters.

Emerson says this meter raises the standard in online density metering by using proven Ni-span C vibrating cylinder technology that is optimised to ensure outstanding performance under varying process and environmental conditions.

The meter's quality is complemented by a new, state-of-the-art, automated calibration facility. Calibrations are traceable to national standards with an optional IEC/ISO17025 accreditation that ensures compliance to the most stringent custody transfer requirements.

The gas density meter also incorporates a new diagnostic capability called known density verification that checks the meter for measurement alarm conditions, sensor integrity and the presence of coating, erosion or corrosion. This expands the availability of diagnostics information in critical density measurement applications and can result in significant reductions in maintenance costs and cycle times.

Meanwhile Honeywell's new RMG gas metering management software and service solution enables natural gas and measuring station operators to monitor operations on-site or remotely, provide data analysis and facilitate remote maintenance. The solution reduces operational costs and improves the accuracy and reliability of measurements.

The system supports both Honeywell and third-party measurement devices, allowing users to determine accurately the technical condition of all gas measurement devices in a metering station using a single software package. In addition, the ability to remotely access measuring devices simplifies planning and organisation, and reduces costs as it keeps station visits to a minimum.

"One of our goals in developing this new solution was to give customers the freedom and flexibility to choose the best combination of measuring devices to meet their unique needs, regardless of the manufacturer," said Frank Michels, general manager, RMG gas metering.

Honeywell has already tested the system with prospective customers including German natural gas distribution network operator Schwaben Netz, producing positive results.

"We're satisfied with our beta test of the gas metering terminal module of the software," said Michael Stoeckle, director of gas network control with Schwaben Netz. "We've found it to be intuitive for our operators to use, as well as robust and stable. We plan on extending our use of the solution in our service department for quick and easy remote diagnosis, and expect a quick return on investment."

Early warnings and PID solutions

The XZR200 oxygen analyser from Michell Instruments offers users added peace of mind with a built-in early warning system that alerts operators of any faults with the unit.

A 3.3 V DC logic output acts as a 'heartbeat' and enables operators to check on the health of the sensor preventing incorrect measurements (Fig.2). False oxygen measurements may result in a faulty combustion process causing higher fuel costs, and leading to loss of revenue or penalties.

The XZR200 sensor is highly reliable with up to seven years life expectancy in clean gases and up to one year in very aggressive conditions such as coal fired combustion.

Michell says the XZR200 capable of measuring per centage oxygen to better than 1 per cent of span (or 0.5 per cent oxygen) with ranges of 0-25 per cent and 0-100 per cent available. The analyser offers four configuration options, with two choices of probe length and two temperature ranges (+250°C/400°C). The lower temperature range (up to 250°C) is suitable for low-temperature applications, while the higher temperature range of up to 400°C serves combustion control.

New from Alphasense is an A-Series photo ionisation detector (PID) sensor. With this, the sample gas is exposed to deep ultraviolet light from a lamp. The emitted light ionises targeted gases in the sample so they can be detected by the gas detector and reported as a concentration (ppb or ppm).

The Alphasense PID can be installed in portable and stationary gas monitors that accept either Alphasense CH-A3 or other manufacturers' compatible pellistor cells. Thus providing complete PID capability in a package that has the same dimensional and electrical profile as Pellistors (providing the electronics input circuit is designed to take the sensor's output range). This opens up an incredible variety of environmental and safety applications, says the company.

SICK Engineering has created a joint venture with GGS Oil and Gas Systems (GGS), a Belgian system integrator, in order to engineer, fabricate and market complex system solutions for gas measurement.

SICK Metering Systems will focus on high-end integrated metering solutions for ultrasonic gas measurement stations. These turnkey stations include, in addition to complete metering systems, filtration and pressure reducing stations, heating installations, ultrasonic flow meters, gas quality analysers as well as interfaces like evaluation and monitoring software. By forming this partnership, SICK Engineering has combined its product expertise in the area of ultrasonic gas flow measurement technology with the systems know-how and service network of GGS, set up to specialise in gas and fluid measurement systems.

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