Krohne's EGM Technology Solves Gas Content Measurement in Pipelines

Gas Content in Pipelines is No Longer an Issue with Krohne EGM Technology! Industrial flow measurements represent one of the most critical components of process instrumentation for many industries. Flow measurements are of considerable importance to the industrial world from the perspective of providing data to automation systems aimed at achieving maximum efficiency as required by current economic conditions, implementing high-efficiency process management, and protecting the maximum interests of commercial parties in purchasing and sales applications. Given the importance of flow measurements, numerous flow measurement methods based on different techniques have been developed to perform volumetric or mass flow measurements. Some of these methods have been developed for liquid applications, while others are designed for gas applications. Today, different flow measurement methods exist that meet the requirements for virtually every type of liquid and gas application. However, the simultaneous presence of gas in the liquid flowing through the measurement pipe is a significant problem for conducting accurate flow measurements. This condition, also referred to as two-phase flow, manifests as the problem of entrained or trapped gas content within liquid pipelines. In many industries, the presence of entrained or trapped gas or air content within pipelines (two-phase flow) has significant impacts on measurement accuracy and process efficiency. While many systems are generally designed to prevent or discharge entrained gas content, the measures taken for this purpose are not always successful or practical. Two-phase flow creates serious measurement problems for most flow measurement technologies. Some of these measurement technologies cannot perform any measurement when gas content is present in the measurement lines, while others detect and measure gas as liquid. In such cases, a measurement error proportional to the gas volume occurs, and as this volume reaches a certain level, flowmeters can cease measurement entirely. To prevent this situation, certain changes to be made in process conditions can lead to changes in flow regime and entrained gas content ratios. The general approach to this issue has been to remove gas or air content from the liquid and conduct flow measurement without gas content. However, it should not be forgotten that while gas content is sometimes an unwanted problem, it may be a requirement for certain processes. In many industries, the fluid to be measured may naturally contain gas, and in such a process, it is clear that separating gas and liquid would not constitute a solution. In such a case, the true solution should be to measure the liquid volume containing gas together with the gas content. The most important flow measurement method capable of meeting these requirements is the Coriolis mass flow measurement method. However, entrained trapped gas content within liquid creates unique challenges even for Coriolis mass flowmeters, which operate by calculating fluid density based on the measurement tube frequency. In a conventional Coriolis mass flowmeter, the measurement tubes have regular oscillation required for measurement in liquid applications without gas content. The lower the oscillation frequency of the measurement tubes, the greater the density value will be (the same holds true in the opposite situation). However, as the gas and liquid portions of two-phase flow move at different speeds along flow tubes oscillating at a specific frequency, the unstable gas content within the liquid will unpredictably disrupt this regular oscillation. Additionally, a range of process factors such as temperature, viscosity changes, pressure, or the relative velocity difference between liquid and gas will also affect flow regime. Thus, variable and complex process conditions cause rapid changes in flow regime and measurement tube oscillation frequencies. In the past, these rapid frequency changes caused signal loss in sensors located on Coriolis mass flowmeter measurement tubes. Such a condition not only resulted in extremely irregular and non-repeatable measurements from flowmeters, but could also occasionally cause a difference in oscillation frequency between sensors, leading the flowmeter to assume a malfunction had occurred and return to reset mode, preventing flow measurement altogether. Facing such a problem, many Coriolis mass flowmeter manufacturers have made efforts to develop different technologies (sometimes limited) to enable their flowmeters to function in two-phase flows, but have approached the problem from very different angles. Confronted with this common problem frequently experienced in the industrial world, Krohne developed EGM (Entrained Gas Management) technology as a standard feature in MFC400 transmitters, the electronic unit (signal converter) of its OPTIMASS series Coriolis mass flowmeters, providing a permanent solution to measurement problems in two-phase flows. Using high-speed digital signal processing and software-based algorithms, EGM technology makes constant and precise corrections at the measurement tube driver level based on real-time frequency information obtained from sensor and driver feedback. These corrections enable the Coriolis mass flowmeter to perform continuous and repeatable mass flow and density measurements across diverse gas entrainment and complex flow conditions. EGM technology allows the flowmeter to maintain oscillations under complex flow regimes, enabling measurement across all possible gas contents from 0% to 100% in liquid flowing media. With this special technology it has developed, Krohne provides seamless, stable, and repeatable measurement capability in the continuously changing flow regimes of liquid lines containing entrained or trapped gas content for Coriolis mass flowmeters. As a result, problems created by gas content in flow measurements are no longer an issue for many applications such as polyurethane foam production in the chemical industry, crude oil flow measurements in the petroleum industry, or ice cream, yogurt, mayonnaise, or beer production in the food industry. This very special measurement capability of Krohne Coriolis mass flowmeters has had the opportunity to prove its uniqueness many times in different fields through the measurements it has performed even under the most difficult conditions since the day EGM technology was first applied.   Can Merter Marketing and Communications Manager Krohne Turkey