Description

Flow monitoring of nitrogen seal gas for compressors

Requirements

  • Recognize leaks and defective seals quickly to prevent compressor damage
  • Indication of the flow

Description

Flow measusrement of sea water for LNG vaporization

Requirements

  • Measurement of sea water for process control
  • Energy balance of heat exchange process

Description

Level measurement in boil off gas recondensers

Requirements

  • Level measurement of gas and liquid in cryogenic conditions
  • Cryogenic temperatures (<-162°C)

Description

Cryogenic LNG measurement to vapouriser

Requirements

  • Cryogenic temperatures (<-162°C)
  • Accurate measurement for process control

Description

Flow measurement during gas odorization

Requirements

  • Injection of odorant in natural gas
  • Indication of the flow of chemicals
  • Ensure continuous injection

Description

Custody transfer measurement of natural gas

Requirements

  • High accuracy measurement of natural gas
  • Need for diagnostics to ensure measurement accuracy

Description

Tank level point detection in LNG storage tanks

Requirements

  • Cryogenic temperatures (<-162°C)
  • Risk of overfill or dry run
  • Inventory measurement

Description

Supervisory and validation software

Requirements

  • Visualisation and monitoring of critical processes
  • Control of reporting, trends and alarm handling
  • Statistical evaluation of measurement data

Description

Metering control cabinets

Requirements

  • Integration of flow computers, PLCs, supervisory computers and printers
  • Installation of single flow computers up to fully redundant cabinet
  • Complying with custody transfer requirements

Description

Sampling and Analyser Systems

Requirements

  • Measurement of gas quality
  • Control of gas mixing process

Description

Custody transfer metering systems

Requirements

  • High-accuracy measurement of gas volume and quality
  • Traceable to international standards
  • Complying with custody transfer requirements
  • Master/duty configuration with flowmeter diagnostics

Overview

Regasification in the oil & gas industry

Converting LNG to natural gas

At the receiving terminal the LNG is stored within very large and extremely well insulated tanks. Custody transfer measurement systems on the delivered LNG and the boil off gas returned to the ship’s tanks to provide accurate accounting data on the received fuel into the terminal. Once the tanker has left, any boil off gas is compressed and re-liquefied in a condenser, or alternatively can be flared off, via a flowmeter.

To supply natural gas into the distribution system, for industrial and domestic use, the LNG must be heated to convert it back to a gas. Typically using the heat available from the sea-water around the terminal, the liquid LNG is evaporated in large heat exchangers fed by seawater. Then the gas frequently has some odour added, as methane has no smell. In the final process the gas is mixed with other gases, such as nitrogen, to adjust the calorific value to suit the local requirement.

On transfer into the high pressure natural gas transmission pipeline grid, the delivery is made via a custody transfer flow measurement skid, where the volume and calorific value again are measured for invoicing purposes.

KROHNE has vast experience with custody transfer and process measurements of natural gas in the gas phase, having provided many such metering installations. For LNG applications, KROHNE developed a series of ultrasonic flowmeters and Coriolis mass meters that can be installed fully insulated when used in cryogenic applications. Other KROHNE flow instrumentation is used in regasification plants to measure process gas flows, heat exchanger seawater flows, nitrogen seal gas flow on compressors, and LNG level control.

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