Confusion over radar level measurement

We have learned not to get too confused over suppliers using buzz-words and clever marketing names, but recently it seems the major level measurement system vendors have been introducing new and higher radar frequency systems as their latest development – and therefore, by implication, maybe the best. We were used to 6 GHz, and then 26 GHz radar frequencies, but why should we suddenly go to 80 GHz? Then, perhaps just to add a little excitement to the mix, Endress+Hauser started talking about 113 GHz!

113GHz_Key_Visual

The E+H radar line up that offers 113GHz!

This article was first featured in the journal South African Instrumentation & Control in September 2017, a journal published by Technews

Let’s dispel a few myths. Firstly, in the same way that lasers for fibre-optic communications systems made the technology available to create infrared optical systems for process gas analysers, and mobile phone technology possibly provided the hardware for the first radar level measurement systems; the 80 GHz versions are a result of measurement technology made commercially viable on the back of production investment in the distance measurement systems and parking sensors used in modern cars. So the suppliers take the available sensors and chipsets to create a new industrial product, and then have to find the best applications – in this case, the ones that might benefit from the 80 GHz.

Secondly, E+H do not have a 113 GHz system, this is a marketing statement, made to catch attention – ‘with a wink’ is their expression. They claim a ‘complete radar competence of 113 GHz’ because this is the sum of the many different frequencies their different sensors use! These are 1, 6, 26 and 80 GHz.

So why have different frequencies?

Possibly the best explanation for the applications suited to the different frequencies has been provided by the Rosemount measurement division of Emerson, in their “Engineer’s Guides”. The Emerson expertise stretches back many years, having acquired the Saab Tank Radar business. Per Skogberg, from the Gothenburg HQ in Sweden, separates the devices into low, medium and high frequency, to generalise.

Radar signals are attenuated, i.e. they lose signal strength as they pass through the air, or vapour, above the liquid. High frequencies are more severely affected than lower. When the air has moisture, steam or liquid droplets (from spray or filling) present, the attenuation is higher. Equally in solids applications, dust particles have the same effect. So low and medium frequency radar are best when there is dust or moisture present.

At lower frequencies, the wavelength is longer (30-50 mm), so surface ripples in a tank have a small effect. At higher frequencies, surface ripples and foam on the surface can be a problem. But the shorter wavelength of the high frequency units (4 mm) allows accurate operation over short ranges, for example in small tanks. The higher frequency units can use a smaller sensor construction, so the unit is easier to install. The beam angle is narrower, so it can be aimed at a smaller target area and therefore can be positioned more easily to avoid any obstructions in the tank. But even this can be a disadvantage, as the installation needs to be exactly vertical and any turbulence of the surface during filling or stirring can cause the signal to be lost temporarily, in larger tanks.

When reading these suggestions, it is important to remember that Emerson does not offer an 80 GHz unit yet, so their marketing approach would naturally bias users to look at low and medium frequency units. The suppliers of high frequency units (Vega, Krohne and E+H) would point out that in many liquid storage tanks the surface is undisturbed, since any foam, turbulence and significant ripples (>2 mm) caused by filling or liquid transfer will only cause short-term interference. Plus the small antenna size and short range performance make 80 GHz units very useful for smaller process vessels and tanks.

Radar system types

There are two types of radar systems, Guided Wave Radar (GWR) and Free Space Radar. The GWR systems use a conducting rod, or similar, extending down into the liquid, often working in a stilling chamber attached to the main process tank. These operate at low microwave frequencies, and are independent of surface turbulence and foam. They are useful for shorter range measurements and interface measurement between liquids, as well as long ranges.

The Free Space Radar systems are more widely used, since they are top-mounted with nothing in the tank: indeed, some can operate through non-conducting windows in the tank roof. Low and medium frequency radar systems generally transmit a signal pulse and measure the liquid distance by the time delay for the returned pulse. High frequency (80 GHz) systems use an FMCW radar measurement, where the frequency of the transmission is swept, and the frequency difference of the returned signal is measured to assess the distance. The FMCW technique is also used at 26 GHz in some recently launched sensors.

Radar systems can transmit their measurement data using 4-20 mA, fieldbus systems like HART, FF, Profibus PA and Modbus, or indeed via wireless systems like Bluetooth. The low and medium frequency pulsed radar systems generally operate over a two-wire interface: some of the higher frequency FMCW systems require more power and use a separate power connection.

Major applications

Simple low-cost radar level measurement sensors have been specifically designed for water industry use, in sewage sumps and flume flow measurement, by Vega and Endress+Hauser. Vega suggest that 40,000 such sensors are now in use in the water industry, mainly in Europe, and claim their total output of such sensors exceeds 550,000 units over the last 25 years.

Several of these devices use simple Bluetooth interrogation and programming from a handheld PDA: E+H demonstrates this at its facility in Maulberg, working on the stream that runs through the factory complex, as seen below.

Micropilot_FMR10_FMR20_on test stream at Maulberg, with operator using Bluetooth

Both E+H and Vega produce further industrial units for use on process vessels, and storage vessels for solids and liquids. Recently, E+H has extended its capability to add long-range units, such as the 80 GHz FMR62, working at up to 80 m range, with an accuracy of 1 mm. Other units work up to 125 m range, at 3 mm accuracy. These units will eventually be aimed at the large petrochemical industry storage tank markets, and specifically are working towards use for custody transfer duties.

Krohne have similarly announced a new range of its 80 GHz Optiwave sensors. Some of these can even operate at up to 700°C, for example for use on molten salt vessels in solar power plants. Lower specification units rated at up to 150°C can be used through a tank roof made of plastic, or similar materials. Suitable for small or narrow tanks, the unit can measure ranges of up to 100 m. Krohne also offers lower frequency Optiwave systems for use on solids and powders, or to electronically monitor the float position in magnetic level indicator columns attached to process vessels.

Postscript: Krohne is organising a webinar with the title “80 GHz Radar Level – Allrounder or Overrated?” to discuss their recent developments with such systems. This webinar will take place on 18th October 2017 at 3pm London time/10am New York time.

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The mystery of intelligent sensor diagnostics @ProcessingTalk #PAuto

The fashion, or trend, that has developed over the last few years for process and analytical instrumentation sensors is to use their on-board intelligence to monitor their own performance status. They achieve this by monitoring and tracking various diagnostic measurements – secondary parameters where consistent values are said to indicate the sensor is working as it should, and has not been subject to any changes since leaving the factory.

This approach is easily understood if you consider the possible effects of exposure of a sensor to excessive temperatures, which might soften the potting or glues holding a sensor to a ‘window’ – and it can be expected that this would be detectable. The addition of a diagnostic sensor, such as a temperature probe, within the sensor housing, could also be an option for checking the sensor condition, and alarming if the sensor exceeds a high or low set-point.

But how else do sensors check their own performance, and how relevant are these “checks”? This topic was discussed in the latest issue of the South African Journal of Instrumentation and Control, August 2017 issue: SAIC is a journal produced by technews.co.za.

Modern (intelligent?) sensors

So, over the past two years of attending and listening to presentations, and reading relevant articles describing the advantages of self-monitoring systems and sensor diagnostics, waiting for an engineer’s explanation as to how the clever monitoring system actually tells the factory instrument engineer anything, it is a bit of a disappointment to report that there seem to be no suppliers that actually make any significant disclosure. This applies across sensors ranging from ultrasonic and Coriolis flowmeters, electromagnetic flowmeters, level measurement systems using radar or ultrasonics, and level alarms. Obviously all the major suppliers are involved in such equipment, and compete with each other, but this secrecy seems a little extreme.

The problem is possibly that until a manufacturer can point to a failure that was detected – or anticipated – using their diagnostics, and decides to publish it, the user population has no idea what systems might actually work. But equally, by publishing a success for the diagnostics, the same manufacturer is saying that one of his sensors failed – and that is a very unusual event, these days. Plus also maybe not something they would wish to publicise.

The older approaches

The whole idea of diagnostics and sensor monitoring has been around for a long time. From personal experience with Bestobell Mobrey, in the 1980s, Mobrey launched an ultrasonic version of a float switch, the ‘Squitch’, which switched a two wire mains connection through a load circuit. When not alarmed it just sat there taking a small control current. For customer reassurance that it was operating in this quiescent state, there was a blinking red LED to show that the sensor was ‘armed’ and operating normally. Mobrey called that a heartbeat indicator, a term that is now used more widely.

For custody transfer flowmeters, the classic approach to validate confidence in the reading is to use two meters in series, and check that both give the same answer. This has progressed to having two separate ultrasonic flowmeters mounted in the same flowtube, on some installations.

For the more safety conscious plant there are often requirements for duplicated sensors for such duties as high level alarms, where two different technologies are used by the sensors – e.g. by mixing float, capacitance or ultrasonic level alarms.

The modern approach

It seems that the ultimate approach is to let the sensor supplier link into your plant automation and data system to interrogate the sensor, and he will verify the measurement and performance diagnostics on a regular basis. With many and varied sensors, this leads to a lot of external interrogation of your plant assets, and possible worries over losing control of your plant.

Overall, it begins to look as though it is becoming impossible for a discerning plant engineer to decide which supplier has the best performing diagnostic system to monitor the relevant sensor’s performance. Rather like opening the bonnet of a modern car, and deciding it would be best to take it to a garage!

At a recent lecture on this subject, held by the InstMC Wessex section in co-operation with Southampton University, a detailed discussion concluded that the sensor suppliers now have all the real expertise in-house and a normal plant engineer could not be expected to cover the depth of this technology for all the many sensors and other equipment within his control. In the end the decision as to ‘which supplier to use’ returns to your own previous experience, including the service and support that has been and is now on offer, and the suitability of the product for the money available for that sensor task.

Power Industry Boiler Water Level Measurement Techniques

The March 2017 Inst Measurement and Control Technical Seminar evening will be hosted by Doosan Babcock in Manor Royal, Crawley, on Tuesday 21st March 2017.

This will be a tri-company, collaborative event, presented by Doosan Babcock, and also featuring contributions from Vega and TC-Fluid Control. It is aimed at providing attendees with a useful insight into industrial measurement application challenges in order to further their professional development knowledge.

Drum Level Control

The first presentation by Doosan Babcock will discuss Drum level measurement using DP Measurement and Hydrastep Measurement techniques.

Power station Steam Drum Level measurement is required for drum level control, Burner Management System (BMS) protection and Code compliance. Drum level is both a critical and difficult measurement to make. At steady state conditions, considerable turbulence in the drum can cause the level to fluctuate. A changing rate of water inflow and steam outflow adds to the potential for measurement error. The DP Measurement technique uses the difference in pressure between a head of water in an external reference column and the level in the drum. The density of water and steam vary appreciably with pressure, so the differential pressure obtained at any given level will vary as boiler pressure changes.

The Hydrastep technique detects the conductivity variation between the steam and the water. The electrode principle is an efficient system for measuring drum water levels.

Microwave Technology

Vega will explain how microwave technology can tackle a wide variety of applications associated with steam boilers. Non-contact or guided wave techniques have the ability to measure reliably, even with fluctuating temperatures up to 450C combined with pressures of up to 400 bar. Measurement is virtually unaffected by pressure and temperature changes. Top mounting makes installation and maintenance easy. In many cases microwave transmitters provide an alternative to legacy equipment for both solids and liquids. SIL qualification and boiler approval now enables microwave technology to  be used directly on steam boilers, with special modifications to compensate for saturated steam effects.

Visual/Glass and Boiler Steam Glass level gauges

untitledVisual/Glass and Boiler Steam Glass level gauges are a requirement on steam boilers for visual verification of the level control system, and will be discussed by TC-Fluid Control. Magnetic level gauges have many applications on and around the boiler, providing visual level indication whilst minimising potential leak paths, and can be used as an alternative to one of the glass level gauges on the boiler drum. Simple, robust technology provides a highly visible indication of process level at pressures of up to 400 bar and temperatures up to 450C.

Postscript: Wessex IMC Section meeting

Vega Controls will also give a talk to the IMC Wessex Section meeting on 15th March about the technology behind their 80GHz radar liquid level measurement systems. The talk will include live demonstrations, and takes place at the Forest Lodge Hotel, at Lyndhurst. A video is available that shows their new sensor.

 

Third-generation to lead E+H UK business

The current Managing Director of the Endress+Hauser UK sales centre, David Newell, has announced his retirement after serving the company for thirty years. He will be replaced by Steven Endress, the first third-generation member of the Endress family to take an operational role in the family business. Steven’s father, Hans-Peter Endress, the former Managing Director and current Chairman of Endress+Hauser UK, will relinquish his duties as Chairman but remain on the Group’s Supervisory Board.

 

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David Newell

David Newell, now 65, boasts 42 years of experience in the process automation industry, of which he has dedicated three decades to Endress+Hauser. He will retire on 30 September 2016, satisfied in the knowledge that he leaves Endress+Hauser as one of the leading suppliers for process instrumentation in the UK. He joined Endress+Hauser in 1986, and became Director of Sales in 1997 – then Director of Sales & Marketing in 2002. After being promoted to Deputy General Manager in 2010, he assumed responsibility for the entire operation two years later. David is married with two grown children and the proud grandfather of two grandchildren.

Third generation of the Endress family

Endress_Steven

Steven Endress

The new Managing Director of Endress+Hauser UK, effective 1 October 2016, will be Steven Endress, who is currently Director of Services at the UK sales centre. Prior to joining the company in 2012, he spent ten years in the software development industry. His previous position was Vice President of Sales at AppSense Inc, in Munich, Germany, where he was responsible for the German, Austrian and Swiss markets. Steven holds a degree in business studies and subsequently received an MBA from Lancaster University. Married with two children, the 37-year-old is the eldest son of Chairman Hans-Peter Endress and grandson of the company’s founder, Georg H Endress.

With Steven Endress taking over the management, Hans-Peter Endress (69) will relinquish his duties as Chairman of the Board at Endress+Hauser UK and concentrate on his work with the Supervisory Board of the Endress+Hauser Group.

Happy retirement David!

(c) ProcessingTalk.info

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Emerson Enardo relief valves get WirelessHART communications

Emerson acquired Enardo, a manufacturer of pressure and vacuum relief valves based in Tulsa, Oklahoma, in late 2013. This week saw the launch of a new wireless enabled version of the Enardo pressure and vacuum relief and safety valve used on storage tanks in the oil and gas, petrochemical and pharmaceutical industries.

Enardo_950_w-bracket

By adding the Smart Wireless monitoring system operating over the Emerson WirelessHART network, the safety valves, normally located on the top of large storage tanks, can easily signal to operators in the control room that they have been triggered to either relieve a pressure or vacuum condition. Such situations can arise as a result of changes in temperature, liquid level, or both, and relief valves are essential to prevent tank over or under-pressure conditions that could lead to structural failure. Enardo pipe-away, vent-to-atmosphere, in-line and end-of-line relief valves are typically installed on storage tanks to control evaporation and fugitive emission losses that result from flammable and hazardous petroleum vapour-producing products. Knowledge of the actuation of such a safety valve enables an immediate response, where needed, to prevent problems which can be related to safety, emissions, and the quality of a tank’s content.

Steve Attri, product manager at Emerson for the Enardo valves, commented: “Until now, PVRVs have remained un-monitored, with none of the feedback loops commonly seen in other pressure control devices. As the tank’s primary pressure control device, this wirelessly-monitored solution can be invaluable.”

Enardo manufactures tank and terminal safety equipment, including hatches, vent, pressure and vacuum relief valves and flame arrestors used in the oil and gas, petrochemical, chemical and other industries. Enardo in-line and stack vent valves have been the oilfield industry standard for more than 80 years.

Prior to the acquisition by Emerson, Enardo had sales of $65m a year, and employed 140 people. It now operates within the Regulator Technologies business, previously known as Fisher Regulators, within Emerson Process Management.

© Nick Denbow ProcessingTalk.info

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Krohne liquid level switch for extreme conditions!

Normally electronically-based process sensors have problems when dealing with extremes of hot or cold temperatures, and can suffer if subjected to high pressures. So the Krohne Optiswitch 5300C is maybe the exception that proves the rule, with a temperature capability from -196°C to +450°C, and able to withstand pressures from zero up to 160 barg (this is -321°F to +842°F, and 0-2320psig). Despite the name, the Optiswitch is a vibrating fork liquid level switch, available with wetted parts in Inconel Alloy 718, with parts in 316L or Hastelloy C-22.

Krohne switch

Optiswitch (pictured sideways for convenience)

This new Optiswitch is designed and fully approved for extreme process conditions, for Overfill protection duties and high/low level alarm, and should find application in the chemical and oil & gas industries, marine tankers and steam boilers. It is available with a variable insertion length, up to 3m long (for vertical mounting from the top of a tank or vessel), and can be used in SIL2 applications, or can be built into a SIL3 redundant architecture set-up. It is a new and significant addition to the Krohne Optiswitch range, which includes models suitable for both liquid and solids/powder applications.

Interestingly the output options available include a DPDT relay, PNP/NPN transistor outputs, or a switched 8/16mA current indication. The latter output was introduced on the Mobrey ultrasonic level switches back in the 1980s, because it seemed like a good idea at the time, but was never really taken up.

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Finland LNG terminal automation

Honeywell Process Solutions will provide its Experion Process Knowledge System (PKS) automation controls, with tank gauging systems, to Finland’s first liquefied natural gas (LNG) import terminal. The imported LNG will be used to supply natural gas to marine vessels and industrial facilities in Finland, helping to replace other fuels that have higher emissions.

The cleaner-burning natural gas will help these vessels and facilities meet emissions regulations in the Baltic Sea and Nordic areas. Honeywell technology (including Enraf tank gauging) is currently being used in about 40 similar LNG import and export terminals around the world.

Additionally, Honeywell’s Enterprise Buildings Integrator (EBI) will connect and power comfort, safety and security systems within the terminal itself, creating a productive environment for workers. With tight integration between the Experion PKS and EBI, operators will have one interface to access and manage all process and facility technology, which improves site-wide visibility and efficiency.
“Honeywell’s technologies offer Skangas Oy an all-in-one solution that will help make their new facility be efficient and productive from day one,” said Pieter Krynauw, vp and gm of the Honeywell Process Solutions Projects and Automation Solutions business unit. “This fully integrated technology will help the terminal maximize its operations with accurate and on time information, precise measuring technologies, safety and security.”
This will be the third LNG terminal equipped for Skangas, one of the largest suppliers of small-scale LNG in the Nordic countries. The company operates similar facilities in Sweden and Norway to provide customers with natural gas for shipping, industrial and heavy-duty land transport needs. The Pori LNG terminal will have a capacity of 30,000 cubic meters and will be completed in the second half of 2016. Honeywell’s tank gauging systems will be used on tanks provided through the Spanish engineering company FCC Industrial e Infraestructuras Energeticas S.A.U.
“Demand for LNG in Finland continues to rise for industrial, shipping and heavy-duty land transport companies,” said Tommy Mattila, Sales and Marketing director, Skangas. “It is critical that this terminal operates at the highest level of efficiency.”
Honeywell technologies that will be used at the facility include:
  • Experion® Process Knowledge System (PKS), the heart of the Integrated Control and Safety Systems (ICSS), which offers more than traditional distributed control systems (DCS) by unifying people with process, business requirements and asset management by enabling integration of all process control, safety systems and automation software.
  • Enterprise Buildings Integrator (EBI) is a building management system that provides a single point of access to information and resources that help monitor, control and protect a facility. EBI will connect fire detection, intrusion detection, access control, video surveillance, and heating and cooling equipment at the new Skangas Oy terminal, and seamlessly share data with Experion PKS.
  • Terminal Manager automates all operations at a bulk liquid terminal, including key monitoring and controlling functions such as product receipt, gate access control and loading.
  • Safety Manager integrates process safety data, applications, system diagnostics and critical control strategies, and executes defined safety applications in a fully redundant architecture.
  • SmartRadar FlexLine is one of Honeywell’s portfolio of high-end radar tank gauges for the assessment of tank contents, tank inventory control and tank farm management.
  • Portable Enraf Terminal is a portable device that enables access and reading of Honeywell Enraf tank gauges regardless of weather or operating conditions.