The short-term trade of liquefied natural gas (LNG) is becoming increasingly common. At last estimate,12% of the LNG market was in short-term (or spot) contracts. The figure is expected to rise to 33% by the year 2011. The increase in short-term trading means that both delivery and loading systems are going to require each party to have a metering system—an arrangement similar to what exists in the oil tanker custody transfer industry.

Please click 'Advantages of Coriolis Meters in the Short-Term Trade of Liquefied Natural Gas' to download the White paper by Emerson Process Management

Case Study by Rotork Valves: The Borwin Alpha platform is the first offshore installation designed to convert AC power into high voltage direct current (HVDC) for onward transmission. Built and designed by the Heerema Fabrication Group on behalf of ABB, the facility can transfer a power of 400MW at a bipolar voltage of 150kV. The converted current is carried by a 200 kilometre cable for onshore connection to the European power grid.

Please click 'Rotork valve actuation supports offshore wind farm technology' to continue reading

Sierra Blog by S. Rouse: In my last post on capillary thermal flow meters, I talked about volumetric flow and how it must be temperature and pressure corrected to obtain mass flow. Wouldn't the world be a simpler place if we could simply measure mass flow directly? In fact, we do! Capillary thermal is likely the most ideal technology for accurately and economically measuring and controlling gas mass flow rate of low flows (under 1000 slpm) and is widely used for this very reason.

During operation, process gas enters the instrument’s flow body and it divides into two flow paths. The vast majority of the gas flow passes through a Laminar Flow Element (LFE) bypass. A very small portion of the total flow is diverted through a small heated “capillary” sensor tube with an ID between .007 to .028 inches. As the gas flows through this very small, evenly heated tube, the molecules of the gas carry some heat from the upstream section to the downstream section. This creates a temperature differential between the two sections which yields the output signal. This output signal is directly proportional to the number of molecules taking the heat away and is thus a direct measurement of mass flow. No pressure (P) or temperature (T) compensation required.

The most common technology in use today for measuring flow is differential pressure “dP or ΔP” (orifice plates, pitot tubes, venturis and the like). Indeed, that was the only flow measurement method I was taught in engineering school. Well, things have come a long way in the 28 years since I picked up my degree. Today coriolis, ultrasonic, vortex, thermal and magnetic flow meters have all found their niches, although dP meters are still the most common due to the large installed base.

Please click 'dP or not dP? Capillary Thermal Flow Meters vs. Differential Pressure Devices—Part 1' to continue reading