Mercury sampling according to ISO 6978-2:2003

Unique features of the LNG Sampler system

Despite the footprint challenge and additional requirements of mercury sampling the ASaP craftsmen (or artists as we like to call them) did an outstanding job to build a very compact LNG sampler and still make everything easy to access for operation and maintenance.

Of course everything starts with good engineering and in-depth knowledge of the current International standards. The ASaP engineering team succeeded in a very challenging task and exceeded every expectation of the EPC, System integrator and ASaP team members involved.

Despite the “manual” sampling, the mercury system was fully integrated and automated by the user friendly ASaP LNG Sampler software.

• The limited footprint available in the existing installation (replacement of a competitor LNG sampler).
• Integration of a mercury sampler according ISO 6978-2: 2003 Sampling of mercury by amalgamation on gold/platinum alloy.

Integrated Mercury sampling modes

The mercury sampling extension on the LNG Sampler system is designed as an add-on system with connection towards the PLC and HMI control system that controls the remainder of the system. The Mercury Sampler system is integrated into the heated LNG sampling cabinet, which has a nominal heating setpoint of 40°C.

The mercury sampling control system is connected to the PLC and HMI of the LNG sampler using Modbus TCP communications over Ethernet.

The Mercury Sampler can be operated in either of the following modes:

• Manual control (i.e., starting a of sample collection on demand of an operator)
• Automatic sequence (i.e., automatic sample collection following the start of an LNG sampling sequence)

Mercury sampling manual control

In manual control mode, the operator must make sure that the system is ready to start collection of sample and per-requisites of ISO 6978-2 sampling procedures are met, including purging. In case the system is not ready for sample collection, the operator needs to ensure that corrective measures are taken before sample collection. In manual sample control, the operator is enabled to enter a specific amount of gas to be passed over the sample trap at the HMI screen. As soon the start manual sample button is pressed, the operator is asked to confirm during the step “traps installed “that the following prerequisites for safe sampling are met:

• That the sample traps have been properly installed in the heated block
• That the flexible hoses have been properly connected to the glass sample traps
• That the sample block valves before and after the heated block are in the open position.

As soon this is confirmed, the sample collection for the specified amount of sample will be commenced at the flow rate set.

Mercury sampling automatic control

To ensure representative mercury sampling during the offload of the LNG, an automatic sampling option is built in. When the automatic mercury sampling is enabled in the HMI screen, automatic mercury sampling sequence will be started as soon as the intermittent LNG sampling is started or when LNG sampling is in progress immediately. The sampling in this case starts from the pre-purging step. In automatic control mode, the mercury sampling will follow the suspend and resume regime of the intermittent LNG Sampler.

Mercury sampling project satisfied customer

“At the request of ASaP this letter may serve as reference.

It is the most advanced design which is currently commercially available on the market. It is the only LNG vaporizer and sampling system which take care for a subcooling of the sample before vaporization. The flange connection avoids any unnecessary heat leak on the sample transfer to the LNG vaporizer system. Due to the flexible design on the orifice and heater system, the flow can be easily adjusted to the process requirements as well as to the required flow rate to overcome the natural heat input to the sample.

There are no moving parts, and it is flexible in configuration. Installation work on site is expected to be kept to a minimum. Operational and maintenance costs are predicted to be minimal. The ASaP solution appears to be the perfect match for a happy customer from the Middle East with regards to technical requirements, flexibility and planning. A return on investment of 1 to 2 weeks is predicted.

The functionality of the system was tested, and the outcome is above expectation. Even without proper insulation on the transfer part, the contact temperature on the bottom part (close to the hot section) was found to be below -150°).”

– Quote from the Factory Acceptance Test (FAT)

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ASaP practical solutions

The practical solutions of ASaP are based on decades of experience, specific education, knowledge of the team members and, last but not least, the joy in our work. The well-established and complementary ASaP package of services and products is an important contribution to the right solutions for your analytical needs. Moreover, the team spirit and the cooperation with specific partners give us the opportunity to design, build, locally install and commission tailor made analyzer systems for you. All these products and systems can be carried out according to the latest guidelines, such as ATEX.

ASaP is a reputable provider of analytical solutions; We can provide you with a full-service package including engineering, manufacturing, offshore service, analyzers, system integration, and cutting-edge LNG Custody Transfer Systems (CTMS), LNG Probe-Vaporizers, advanced LNG Samplers, and precise NG analysis systems. You are kindly invited to consult us on any analytical challenge!