the chemical engineer|issue 882/3|dec 2014/ jan 2015

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GLOBAL demand for products from refineries and petrochemical plants is expected to grow steadily in the

coming years. To gain an advantage in a dynamic market, plants are increasingly automating a wide range of operations. Although this automation is extending throughout and beyond enterprises, its value remains highly dependent on the ability to use field measurement data to optimise performance, efficiency, and safety. Today’s measurement technology enables plant operators to turn data from critical assets such as pump and valve networks into digital intelligence. In doing so, they can make critical decisions more quickly by capturing, managing and analysing the right production information at the right time.

the petchem challengeHistorically, the refining and petrochemical industry has presented equipment suppliers and production personnel with demanding operations. For field equipment such as pumps and valves, that has translated into an increasing need for more accurate and robust performance. Pumps play a key role in plant operations,

Flow: getting cleverTim Vogel describes how advanced flow measurement technology turns

data into digital intelligence

from start to finish. They are used in applications where corrosive, toxic, and flammable fluids are metered under very high pressure and extreme temperature. Control valves are equally important to safe and efficient production processes. Pump and valve networks deliver information crucial to running modern industrial facilities. However, they frequently reside in ‘islands of automation’, where there is no unified infrastructure to ensure those who actually need the information can receive it quickly enough to take action. Plant operators seek to monitor all intelligent field instruments throughout the facility, so they can share relevant, real-time

information and knowledge. For example, valve performance must be monitored and carefully maintained to achieve proper pump system operation. But there are additional instruments working in association with this equipment, such as flowmeters for measuring fluid that passes through the valves and pumps.

In order to be most effective, refineries and petrochemical plants must take a holistic approach to data capture in their production and business environment, with integrated platforms and seamless data exchange between automation and the plant floor, production and operations management.

critical operational demandsWith a stringent regulatory environment, human resource shortages, requirements for sustainability, and the need to act with agility, it’s important that vital plant information is received in context – when and where it’s most valuable.

In modern field measurement systems, data is collected by hardware but organised and presented by software. Substantial increases in hardware accuracy are no longer

In order to be most effective, refineries and petrochemical plants must take a holistic approach to data capture in their production and business environment, with integrated platforms and seamless data exchange.

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attainable, so the main driver of business results is now the data itself – organising it, collecting it alongside information from elsewhere in the plant, presenting it in a way that makes sense to operators, and then using the data to improve overall performance. Most field measurement and metering units currently monitor a single process element and present it individually. Companies are looking for intelligent software solutions to integrate disparate assets throughout the process so that data from the point of receiving the product, through production equipment, is fed into a central hub where it can be used to make highly-informed production and business decisions. One of the advantages to this approach is that manufacturers can provide information and tools specific to worker roles without much customising or configuration. Having a single infrastructure spanning production processes enables faster identification of problems, better planning, and greater organisational flexibility.

importance of flow measurement to pump and valve networksGathering this data and collating it begins at the point of product entry. Because of the multitude of operations in a refinery or petrochemical plant, there is a complex system of material and energy flows. From incoming crude to outgoing products, everything is flowing – and for safe and efficient operation, these flows must be measured. The typical process industry facility has two key flow measurement requirements: accuracy and cost. Many flowmeter applications are antiquated, or were part of a large-scale replacement programme throughout a plant. The challenge is to correctly match the right flowmeter to the right application in order to achieve the best performance for the lowest cost. Flow metering most commonly takes place

as product enters the refinery or plant, and monitoring flow accurately is important to operators for four reasons:

• safety: modern flow measurement devices can self-assess, meaning they can alert operators when they are receiving anomalous data or need maintenance. This ensures that no faulty equipment is in use (either the meter itself or the pipe it is monitoring).

• downtime: refiners and petrochemical producers are under pressure to avoid downtime, which can cost millions per day. Process plants must operate 24/7 if they are to be profitable.

• product evaluation: depending on the area, there are different types of product that a given refinery or plant can receive. There is a need to detect not just the flow, temperature and pressure of the product, but also its energy (component make-up). With an accurate idea of product energy, an operator can optimise processes to maximise profit (eg extracting hydrocarbon and selling it separately).

• product measurement: The most obvious requirement for flow meters is measuring the amount of product, so that operators have a comprehensive overview of what they’re getting and know they’re not being overcharged. Previously, an operator might have to take the supplier’s word on the amount of product received.

With reliable, accurate data on process flow conditions, companies can not only boost their output, but also begin to harness the information alongside readings from key points throughout the facility to present a clear, concise overview to operators.

innovations in metersTraditionally, refining operations have used coriolis, orifice and vortex meters to measure process flows, especially in demanding environments. These conventional meter designs have well-documented shortcomings. Intrusive sensors create pressure loss, reducing process efficiency. They also require

frequent servicing due to their contact with hot and often dirty hydrocarbons. Such high-maintenance measuring technologies can cause a host of asset management headaches. Ultrasonic flowmeters are now regarded as a preferred technology for many process plant applications, particularly measurement of gas where it enters the refinery or plant. These meters employ robust transducers generating repeatable pulses (amplitude and frequency). They also include high-speed electronics complete with an accurate clock to detect, resolve and time the transmission/reception of sonic pulses with sufficient time domain resolution. The meters’ transducer and electronics configuration permits high pulse transmission rates, and transit time measurement allows rapid integration of fluid flow velocity so accurately-measured values can be reported once per second. The most important development in ultrasonic technology in recent years is the development of multipath meters, which are designed to average axial velocity components over the cross-section of a closed pipe. The benefits of ultrasonic flowmeters include:• trouble-free operation at wide range of parameters (eg temperature, pressure, etc)• no clogging, even with dirty or fouling fluids• no pressure loss• maintenance without process interruption• no risk of leaks• accurate and repeatable, even at low flows• wide dynamic range• independent of fluid or changing pressure• inherently bi-directionalUltrasonic flowmeters are superior to legacy systems as they are more accurate, are self-assessing, require less maintenance, and can be inspected in-line without disturbing the process piping. Conversely, the need for mechanical meters to be periodically tested and repaired means they have to be removed Plant operators need access to vital asset information when and where it’s most valuable.

Figure 1: Ultrasonic multipath meters measure average axial velocity components over the cross-section of a closed pipe

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from service, forcing users to either replace the meter with a temporary device or cease operation until the meter is refitted back into the line.

latest software developmentsOne of the key advantages of ultrasonic flow meters over all other flow measurement technologies is the availability of diagnostic information beyond just delivering pulses or signals proportional to gas volume. The latest designs use electronics that optimise internal diagnostics, flow velocity calculations, signal processing, data storage, interface to flow computers and supervisory control and data acquisition (SCADA) systems, and field service diagnostics tools. The new generation of ultrasonic meters incorporates parameterisation and diagnostics software as an interface to robust condition monitoring capabilities. The software can display data systematically in clearly-arranged tables and allow selected measured values and parameters to be combined at the user’s discretion (see Figure 2). First, the software monitors the health of the meter and warns if there are any pending problems (eg blocked flow conditioner). Secondly, it monitors the gas process and alerts when there are any upset conditions (eg liquids in the gas stream). Thirdly, the software monitors calculated metering uncertainties and provides alarm notification. One of the criteria common to many ultrasonic flowmeters is peak identification and quantification of position and amplitude in the pulse envelope. However, most meter suppliers avoid using comparative analysis of pulses, or ‘stacking’, since it is a burden on signal processing in noisy and turbulent environments – resulting in either data refresh rates exceeding one second, or a reduction of evaluated samples falling below statistical acceptability. For improved signal processing capabilities, ultrasonic meter software designers have implemented additional qualitative analysis techniques to evaluate the pulse envelope and identify ultrasonic pulses, while still maintaining high firing rates. Such innovative detection algorithms are key to insensitivity to noise from valves and other inline systems in many refinery and plant installations. For users, testing for system delay time and adjustment is a critical requirement. Besides the time-of-flight of the ultrasonic pulses, delay times caused by signal-processing electronics, properties of the transducers and calculation algorithms can occur within the system. The use of ‘live’ precision time delay adjustment capabilities enables precise

adjustment of delay time and avoids the disadvantages of related testing procedures. It also preserves measurement uncertainty resulting from in-situ auto calibration of system delay (Tw) after field replacement of transducers.

looking to the futureThe software employed in field measurement equipment currently relies, in part, on human input. This is the most vulnerable part of the process and the most likely to encounter error. Automation equipment suppliers are seeking to automate this function as much as possible through artificial intelligence (AI), which will allow technology to make the logical leaps and intuitive assumptions people are now relied upon to perform. Emerging AI technologies will allow refining and petrochemical firms to turn data from field networks into digital intelligence that helps operators make critical decisions faster by capturing, managing and analysing the right production information at the right time. In the past, decision-makers had to be highly technical experts to make sense of the data in front of them. The goal now is to minimise training requirements for personnel, with intelligent software solutions bridging the gap in expertise by presenting data in a more user-friendly way. AI will not only allow robust information to be presented to operators, but will also support informed advice/suggestions on appropriate actions when data is delivered.

These suggestions will be backed up by decades of historic data and previous decisions and outcomes.

conclusionWhile petroleum-based products have generally always been regarded as precious commodities, the current business climate has made the need to accurately measure production values all the more critical. Refineries and plants are finding new ways to use digital intelligence from assets such as pumps, valves and flow meters to make faster and smarter decisions affecting their operational and business performance. tce

Tim Vogel (tim.vogel@honeywell.com) is product marketing manager, gas metering, at Honeywell Process Solutions

hpsmarketing@honeywell.com

Chemical Engineering MattersThe topics discussed in this article refer to the following lines on the vistas of IChemE’s technical strategy document Chemical Engineering Matters:

Energy Line 1

Visit www.icheme.org/vistas2 to discover where this article and your own activities fit into the myriad of grand challenges facing chemical engineers

Figure 2: The new generation of ultrasonic meters display data in clearly-arranged tables that enable users to combine selected measured values and parameters when needed