False alarms from safety sensors?

So I do know about sensors and control systems, from the supplier point of view. But maybe like many suppliers I’ve only been on site to troubleshoot a sensor that is reported to be giving incorrect data. So someone else made the decision to question the validity of the sensor outputs.

These days, the nearest I get to regular sensor monitoring is at home, typically with smoke alarms, a CO monitor, and a flammable gas alarm. Plus the plant manager, my wife, is always demanding an immediate solution to any alarm system going off, to continue production.

The problem

A flammable gas alarm was positioned above the gas hob: perhaps in retrospect not the best place, as the instructions said humidity and steam should be avoided. But very quickly we realised that the detector was not very tolerant of any wine added to dishes being cooked on the hob. Then, surprisingly, it alarmed whenever we had bread dough baking in the (electric) oven. Since the detector was said to be set to alarm at 25% of the LEL this was surprising.

DSCN6511

The instruction came down – ‘Get me a switch in that alarm circuit, so I can switch the piercing noise of the alarm off!’ So, there was my solution, and a task, so that was done. I did not think it through any further.

Time passes

This system worked well for maybe 3 years. The alarm switch changed power from the alarm to a lamp over the worktop, so we knew to switch it back on after a problem event. But such sensors must have a life, and so when the alarm started going off when the kettle boiled and steam drifted up past the detector, I thought the unit was failing. There were then several late evening alarms, for no apparent reason, and we could not smell any gas (it is difficult to detect these days), nor see anything untoward. Like every engineer I guess, I felt the sensor, to find it very hot. This seemed to confirm the problem, that the sensor was failing, so take the thing out – ‘it was not that hot before!’ Something had changed.

Six months later, this Summer, we had a new gas meter – a Smart unit – installed on the domestic gas supply. Ultrasonic measurement of the flow, wifi connection to the indoor display, and mobile network reporting usage figures to the supplier. That would all be great, except the fitter refused to reconnect the gas to the house, because of a slight leak detected indoors. We had to call out a plumber to deal with our in-house problems. Good job it was Summer, as that took over a week.

Finding the gas leak

The leak was located as somewhere in the piping to the gas hob. The plumber tightened up the connections under the hob, and repeated the pressure loss checks. Still a slight leak, but within allowable tolerances. OK, so he checks once more, to be sure, and starts his paperwork. A last twist of the 90 degree bend directly on the hob (supplied by the Chinese supplier) produced an interesting result: the threaded part of this connector sheared off, almost in two half-round pieces. It looks like steel, but low grade steel, and showed a brittle type fracture all around the fitting.

Presumably the crack that had been there before, allowing a slow leak, had led to the fracture on tightening the connection. That was installed 10 years before, and no-one had done any checks of that or the system post installation. OK, I had never had the systems tested for gas leaks.

What had happened?

The conclusion at this point was that the slow leak presumably collected gas in the lower cupboards, and when this escaped it combined with the wine vapours to trip the alarm. Possibly the steam from the kettle just accelerated the rise of the gas past the detector. The detector was presumably a Pellistor, and got hot because it was burning the gas off. The dough rising in the oven? I don’t know much about bread and dough – but the leak was directly above the oven, so maybe the gas and air, warmed from the sides of the oven, helped the gas rise up past the detector. If that fitting had actually failed totally one night, there would have been a major blast, as I had removed the gas detector.

We now have installed a new detector, further from the cooking (3 metres). Plus the old one is re-installed, as a back-up unit: it is working OK still, next to the boiler. The bad news: the new alarm went off last weekend, when simmering a Paella laced with white wine….

Yesterday the plant manager produced a batch of dough and made bread. Both flammable gas alarms went off, first the unit 3 metres away then the old reserve unit, now even further away in the utility room, with the boiler.

Legislation

In any rented accommodation the landlord has to have a gas system safety check once a year. Because we own our own house there is no such requirement, and the boiler service man, who checks the gas boiler and heating system once a year, is not required to, and does not include, a system gas leak test in his inspection.

Product or system failure?

The gas hob was made by Proline, and installed around 8 years ago by a registered installer. It was a Chinese manufactured unit supplied by Comet as a low-cost own-brand hob to many retail outlets in the UK. The 90 degree bend that failed was supplied as a part of the hob, the gas inlet port. It is not steel, it could be an aluminium or zinc alloy. It appears the design was such that this port could be stressed during installation or tightening, as the bend itself would not rotate to suit the angle of the delivery pipework. It seems the break was on the hob side of the fitting. A combination of a poor quality fitting and a poor design.

The flammable gas alarm seems to work OK in detecting natural gas, but is even more sensitive to alcohol vapours, bread and dough making, and using any window cleaning spray that has any hydrocarbons in the fluid. So beware of using them in a brewery, distillery, bakery, bread shop, pub, restaurant and so on!

There was undoubtedly a small gas leak, around the hob, which has now stopped. Possibly this was from the 90 degree bend fitting, which then completely broke apart on tightening the joint. It remains possible that this failure was an accident waiting to happen.

The domestic plant manager is none too pleased at the moment. So do I leave the sensors installed, take both or one of them away, or fit switches to suppress the noise and turn off the alarm(s)?

UV keeps bottled water safe

Hanovia UV has supplied Cott Beverages UK, based in Derby, with a PureLine intelligent UV system to keep its production process water pure.

PureLine range

In an increasingly regulated and safety-conscious market, legislation such as the EU Directive for Bottled Water 98/88/EC (1998) drives the beverage industry to meet ever more stringent standards of quality. Microbial growth due to contaminated water or ingredients can cause discolouration, off flavours and shortened shelf-life. The threat of contamination is further increased as manufacturers respond to demands for less chemical additives and preservatives. Effective microbial disinfection of the whole process is therefore essential.

To meet this requirement, Cott Beverages has been using Hanovia UV disinfection technology to treat process water used in the production process. The company decided to use UV technology to ensure final product security prior to mixing and bottling and has been very satisfied with the performance of the UV systems.

“The Hanovia UV systems have been easy to integrate, maintain and operate,” said Chris Prentice, site service engineer at Cott Beverages. “They provide us with absolute insurance before bottling by making sure that we are producing and maintaining a high-quality product, which is essential for our brand.”

PureLine UV from Hanovia is an intelligent system that is optimised for the beverage industry to simplify the treatment of water, sugar syrup, brine and even reducing chlorine and ozone. Critically, there are no microorganisms known to be resistant to UV – this includes pathogenic bacteria such as listeria, legionella and cryptosporidium (and its spores, which are resistant to chlorination). Unlike chemical treatment, UV does not introduce toxins or residues into process water and does not alter the chemical composition, taste, odour or pH of the fluid being disinfected.

UV is used for both primary disinfection or as a back-up for other purification methods such as carbon filtration, reverse osmosis or pasteurisation. Because UV has no residual effect, the best position for a treatment system is immediately prior to the point of use. This ensures incoming microbiological contaminants are destroyed and there is a minimal chance of post-treatment contamination.

UV disinfection systems are easy to install, with minimum disruption to the plant. They need very little maintenance, the only requirement being the replacement of the UV lamps every 9-12 months, depending on use. This is a simple operation that takes only a few minutes and can be carried out by trained general maintenance staff. The Hanovia UVCare training programme supports businesses like Cott Beverages to make sure servicing is carried out by certified engineers at all UK production sites.

Yokogawa EPMS and SCADA for the UK’s BPAL pipeline system

Yokogawa has received an order from the British Pipeline Agency Limited (BPAL) to supply a management and control system for one of the UK’s major multi-product fuel pipeline systems, to replace the current BPAL pipeline management and SCADA systems.

The BPAL UK pipeline system consists of three integrated multi-product fuel pipelines that link two, refineries, one at Ellesmere port on the Mersey near Liverpool and the other on the Thames in Essex, to inland distribution terminals. These pipelines, operational since 1969, meet over 50% of the jet fuel needs at London’s Heathrow and Gatwick airports, and are altogether some 650 km in length. BPAL, jointly owned by Shell and BP, are the operators of these pipeline systems (known as UKOP and WLWG), which are owned by a consortium of partners.

This order is for Yokogawa’s Enterprise Pipeline Management Solution (EPMS), which will manage functions such as delivery scheduling and oil storage, and their Fast-Tools SCADA software, to monitor and control the oil pipelines and related equipment such as compressors. The EPMS uses specific gas and liquid applications that enable a pipeline operator to manage delivery contracts in a time and energy efficient manner. With the SCADA system covering monitoring and control, the EPMS will integrate the management of the SCADA data. Delivery of these systems will be completed by March 2018.

Further order for UAE Power and Desalination Station

Yokogawa also recently received its first ever DCS order for a power and desalination plant in the UAE. The company is to supply the Sharjah Electricity & Water Authority (SEWA) with control and safety systems, plus field equipment, for Units 7 and 8 at the Layyah Power and Desalination Station.

Each unit comprises a 75 MW oil and gas-fired thermal power plant and a 27,000 m3 per day multi-stage flash (MSF) desalination plant: a technology that involves the heating and evaporation of seawater in multiple vacuum distillation tanks to produce steam, which is then condensed to produce fresh water. Such systems are energy-efficient because they use the heat from the steam that is created in the vacuum distillation tanks.

Yokogawa Middle East & Africa will deliver the CentumVP integrated production control system for the boiler, turbine governor, turbine protection system and the desalination plant at each of these units, as well as the ProSafe-RS safety instrumented system for burner management and boiler protection. The field instruments will include Yokogawa products such as the DPharp EJA series differential pressure and pressure transmitters, continuous emission monitoring systems (CEMS), and steam and water analysis systems (SWAS). In addition to being responsible for engineering, the company will provide support for the installation and commissioning of these systems, with all work scheduled for completion by September 2017.

Demand for electricity and water is soaring throughout the Middle East due to their rapid economic growth. Power and desalination plants that rely on the region’s abundant oil and gas resources make up an important part of this region’s infrastructure.

Regular educational reading?

The regular eNewsletter from the UK journal HazardEx should be compulsory reading for any process engineer: it always restores your faith in the incompetence of the human race when doing any project, and confirms that if anything will go wrong, it will do! There must have been someone’s law that said that.

Choose a relevant report to your industry from the fascinating selection in the current January 2017 issue, available from www.hazardexonthenet.net:

  1. A Tesoro Logistics oil pipeline spilled 20,600 barrels of oil back in 2013, at a site near Tioga, North Dakota. Four years later the clean-up is still continuing, and it is likely to go on throughout 2017. Another spill of shale oil was discovered on December 5th by a landowner near Bellfield, North Dakota. There’s a lot of space in North America, but this bit seems to have collected 4200 barrels of oil, apparently from a pipeline owned by Belle Fourche, part of True Companies of Wyoming. The relevant Administration has issued a corrective notice, lets hope that will be completed inside five years!
  2. In Shaanxi province, China, a public toilet in Yulin City exploded on January 1st, killing one person and injuring seven others. Presumably someone lit a cigarette, and ignited an explosive build-up of sewer gas present in the building, which collapsed following the explosion.
  3. An explosion at the Airgas plant near Pensacola, Florida last August unfortunately killed one worker: the explosion destroyed two tankers and a large tank storing nitrous oxide. The unexpected consequence was a country-wide shortage of canned whipped cream and other popular toppings over the Christmas break – obviously much more important to the US public! (These cans use N2O as a propellant and preservative)
  4. The explosion at the GlaxoSmithKline Irvine plant in Scotland in July 2013 injured two employees: SmithKline Beecham Ltd pleaded guilty to H&S failings and was fined £55,000 in court in December 2016.

P+F buys ecom to complete hazardous area capability with mobile devices

Ecom instruments from Assamstadt in Germany was established 30 years ago, and has specialised in portable equipment suitable for use in the most hazardous areas of a plant, ie Zone 1 rated explosion hazard areas on a petrochemical plant, etc. This extends from a torch, through to a mobile phone, PDA, laptop etc, as well as measuring instruments and calibration equipment. They recently developed into providing similar barcode scanner systems, plus intelligent software and applications.

At the end of October it was announced that Pepperl + Fuchs of Mannheim, also in Germany, a family-owned company well known for industrial sensor systems and explosion protection in general, had acquired the whole business of ecom instruments GmbH. In this way P+F adds to their existing (static) explosion protection portfolio and know-how offering by including mobile devices and solutions.

Dr Gunther Kegel, CEO of P+F, commented “In ecom instruments we found an industry pioneer with 15% growth rate lately who, for decades, proved and strengthened his technology leadership in mobile explosion protection and now complements our offering with a competitive portfolio reaching far into the future”.

“Besides the expanded product portfolio we can see new opportunities arising along the entire value added chain. With this we can not only strengthen our offering in the field of explosion protection, but we can achieve a much better market position – with a partner from our region – and consequently generate new solutions around the complex of Industrie 4.0”.

Rolf Neid, the Founder and Managing Partner of ecom Instruments, commented: “The expertise in explosion protection and the wide-spread international sales force of Pepperl+Fuchs made them our favourite partner from the very beginning. Our innovative devices do not only fill a gap in their portfolio, but allow ecom instruments and Pepperl+Fuchs to develop future business models and solutions at the Center of Competence at Assamstadt to gain access to the enormous growth potential of the ongoing digitalization of industry”.

P+F hazardous area business

The P+F Process Automation Division is world-market leader in the field of explosion protection in hazardous areas using intrinsic safety. Furthermore, the Division offers large varieties of application-oriented system solutions for process industries. The portfolio consists of analogue isolation barriers, fieldbus topology systems, remote I/O systems, HART interfaces, level control sensors, purge systems, HMI devices, as well as power supplies and signalling devices.

The P+F UK factory in Wednesbury, in the Midlands, produces Exd and Exe junction boxes, cabinets and control panels and switching systems for hazardous area use, plus accessories such as light fittings, floodlights and beacons for hazardous areas. The factory, originally known as Walsall Ltd, was acquired by P+F in 2009, and a visit to see the expanded operation in 2012 was reported on Processingtalk.info – see the story “P+F invests in factory for Exd, Exe housings

Emerson acquires PermaSense

Emerson has announced the acquisition of UK-based Permasense Ltd, a leading provider of non-intrusive corrosion monitoring technologies for the offshore and onshore oil production, refining, chemical, power, pipelines, metals and mining and other industries. Permasense monitoring systems use unique sensor technology, wireless data delivery and advanced analytics to continuously monitor for metal loss from corrosion or erosion in pipes, pipelines or vessels, and reliably deliver high-integrity data from even the harshest environments.

The acquisition represents another step forward in the Emerson strategy to invest in its core business platforms and expand in markets that hold significant long-term growth opportunity.

“Corrosion and erosion can significantly impact the safe and reliable operation of our industrial customers’ infrastructure, which can have dire consequences. Wireless non-intrusive corrosion monitoring is a transformational shift that helps customers immediately understand the health and integrity of their infrastructure in real-time and enables them to fully optimise their operations while maximising safety,” said Mike Train, president, Emerson Automation Solutions. “For example, with the increasing complexity of the types of crude oil coming into a refinery, corrosion is becoming a significant issue in the uptime and profitability of a refinery. Now refinery infrastructure can be monitored and controlled using this non-intrusive technology.”

The Permasense product line will become part of the Rosemount portfolio of measurement and analytical technologies. Permasense technologies complement the Emerson Roxar intrusive corrosion monitoring and non-intrusive sand management systems and strengthen the company’s Pervasive Sensing applications that provide customers a more complete view of their operations and facilities. With Permasense and Roxar technologies in its portfolio, Emerson will be the largest provider of integrity and corrosion management solutions in the marketplace.

Lal Karsanbhai, group vp, measurement and analytical technologies, Emerson Automation Solutions, added: “The addition of patented Permasense technologies along with our existing Roxar technologies enables Emerson to provide customers with a more complete corrosion monitoring solution and a clearer picture into the performance of their infrastructure based on what they’re demanding of it and the strategies needed to optimise production.”

Central to Permasense corrosion monitoring systems are sensors that employ proven ultrasonic wall thickness measurement principles. The sensors are battery powered and communicate wirelessly, which minimises the cost of installation and enables use in remote areas and on a large scale. The sensors are also designed so they can be deployed in hazardous areas.

man-adjustpipe

Noise mapping offshore using wireless sensors

Many of the latest technology developments in relation to offshore oil and gas production installations have emerged from Norwegian research studies, because that industry represents the major part of the economy in Norway.  Such research studies do not only relate to better and more efficient methods of working, but they also investigate the health and safety aspects of the industry: an area of particular concern has been hearing damage to workers offshore, which is the predominant cause of work related illness. At the Yokogawa User Group meeting held in Budapest in May 2016, Simon Carlsen of Statoil ASA in Norway explained the background to a recent project that was undertaken to improve the efficiency of the noise surveillance and monitoring systems Statoil use offshore. This was also presented to a Society of Petroleum Engineers International conference on Health and Safety in Stavanger in April (Ref 1).

picture-3-from-pdf

The main Health & Safety tool used for monitoring noise exposure is the ‘Noise map’, which provides noise level contours within rooms and around machinery where workers are active. These are used to establish a course of action where noise levels exceed allowed limits, whether this action is to reduce or remove the noise source (if possible), insulate the area, issue PPE to workers, and/or impose working time restrictions. Noise maps have historically been based on manual surveys that take single point readings, which are then plotted onto a site map, typically from CAD drawings. Manually taking and plotting these measurements is arduous and time consuming, and typically would be updated only on around a four year cycle. Plus the readings are (obviously) not continuous, only record the conditions when each reading was taken, and generally do not record the added effects from workers using different machinery and tools in the area.

Statoil R&D on wireless & noise instrumentation

Simon Carlsen of Statoil joined the R&D Department in 2006, bringing expertise in wireless instrumentation, and started investigating the feasibility of using wireless sensors and software techniques to create a real-time noise map. The system subsequently commenced became known as WiNoS, for “Wireless Noise Surveillance”, when formally initialised in 2013. This will consist of a network of wireless noise sensors, continuously monitoring the noise in the process area, using sound pressure level (SPL) measurements of four types: A-weighted SPL (I.eqA), C-weighted SPL (I.eqC), peak SPL (I.peak) and thirty one separate third-of-an-octave frequency band measurements from 25Hz to 16kHz. This data is much more comprehensive than the simple noise level measurements used to establish the noise maps, but will superimpose this data onto the historically available maps. These readings can then be used to update the map in real time, and create alarms available to operators.

The WiNoS sensors then use an industry standard wireless network infrastructure, which transmits the data into the control system, where special software produces the updates to the noise maps – typically on a one minute update rate (ie almost continuous). This live information can be used to create alarms to report back to workers in the area, to control their noise exposure. The objective is to reduce work-related hearing damage, by knowing the actual on-site conditions; to optimize operator time working on/near tools, to reduce daily exposure; and to provide instant feedback on the effect of noise reduction measures. In addition WiNoS allows for time synchronized measurements amongst the sensors in the network, and also allows the control room operator to trigger a download of a high resolution frequency spectrum waveform from any sensor of particular interest, to analyse the signature of the noise. This latter is a major part of the future development of the monitoring system, which will feed into plant condition and process performance monitoring studies.

noise-map-3

The WiNoS project development employed the expertise of the Norwegian companies Norsonic AS in the microphone design and the sound level measurements, and the Department of Acoustics at the research company SINTEF to develop the PC software that records the data and creates the noise maps. The software was also required to conform to the Statoil qualified communications protocol.

Choice of wireless network

A major part of the research feasibility study that preceded the WiNoS project was devoted to the choice of the wireless network to be used to efficiently and reliably transmit the data, relatively continuously from multiple sensors. The two suitable networks that were emerging at that time were WirelessHART and ISA100.

The WirelessHART system is now well-known and fairly widely used in Statoil facilities, but the early research trials showed mixed experience with the system and the relevant vendors – some of this was related to the lack of specification details written into the WirelessHART standard. But there were also challenges with achieving the power efficiency in the transfer of all the data required, and the requested large data transfer of the high-res waveform was not readily achievable.

The ISA100.11a wireless transmission standard was also in use in Statoil, and had been adopted for the wireless flammable gas detector pioneered by GasSecure in Norway – Statoil had been involved with the prototype field trials offshore. The initial trials on ISA100 equipment from Yokogawa provided high flexibility for the different application demands, allowed all the 31 one third octave values to be packed into one transmission telegram, and allowed a well-defined block transfer. The sensor could also achieve the two year life required from the installed battery pack, at the 1 minute update rate.

The decision was made that ISA100.11a was to be the preferred protocol for WiNoS, from a technical and project model perspective. Based on the earlier experience of development co-operation with Statoil, it was decided to invite Yokogawa to join the WiNoS project as a Co-Innovation partner, a role that they were keen to develop. In addition to providing the ISA100.11a wireless interface electronics for the sensor, and the interface into the third party control system, Yokogawa worked with Norsonic to develop the mechanical housing for the microphone sensor, and the electronic hardware to process the sound measurements using the Norsonic software, with the whole sensor assembly meeting ATEX requirements.

yta510iaeueth-xx

A Yokogawa wireless temperature transmitter adapted to include the Norsonic microphone

Full system test

In March 2016, a network of 7 off Yokogawa ISA100 enabled wireless noise sensors were tested within the (land-based) industrial lab hall at Statoil Rotvoll, in Trondheim, which has dimensions 35x25x15 metres – and contains various pumps and process equipment. Further synthesized test noise sources were created using loudspeakers. The wireless sensors, the noise mapping software and the IT backhaul architecture all operated reliably and successfully.

winos-system-test

Dynamic noise map generated with the system test

 

A further test, offshore on an operational Statoil platform, is planned and scheduled for Spring 2017, for which Yokogawa will supply 20 production sensors and the ISA100.11a wireless system. A typical platform deck of 50×50 metres might in practice require around 12 noise sensors for effective coverage.

isa100_yta-a-xx

Possibly future noise mapping sensors will be added in high noise plant areas

The Statoil WiNoS system is now ready for development into a commercially available product for use as an offshore platform noise mapping tool. Future research on this system will involve investigation of 3D noise mapping systems. Statoil consider that the equipment application has potential for expansion into machinery condition monitoring, to include automatic process upset or fault and leak detection.

© Nickdenbow, Processingtalk.info, 2016

References