Chemical Technology November 2015

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Contents REGULAR FEATURES 3 Comment by Fred M Hayward, Senior Higher Education Advisor, University of Massachusetts, Amherst, USA 32 IchemE SAIChE news 36 Sudoku No 109 and solution to No 108 / Et cetera COVER STORY 4 Optimising chemical plant efficiency: Technologically advanced instruments can hold the key to boosting productivity Chemical plants seeking improvements in productivity and efficiency mostly find that the fastest and most cost-effective manner to reach their goal is through the installation and modernisation of process automation systems and advanced field instruments. NANOTECHNOLOGY 6 Blurring the lines between nanotech and biochemistry Korean Scientists at the Center for Nanoparticle Research, IBS have come up with a ‘fabric’ made of ~150 nm dia silver nanow- ires in an interlocking coil, and embedded in elastic material. This conductive fabric can be linked to a small battery and provides direct heating over and around the joint. Because it is light-weight, wearable, and breathable, it can be worn while running around. by Gavin Chait

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CONTROL AND AUTOMATION 20 Rethinking automation

The automated factory environment was envisioned and built decades ago to meet the needs of manufacturers producing high volumes of mass-produced products. Today, unprecedented change is taking place. Information from Rethink Robotics, Inc, 27 Wormwood Street, Boston, MA, USA

23 Focus on control and automation

MINERALS PROCESSING AND METALLURGY 26 What challenges are faced when performing EPCM and EPC projects in Africa? Africa is a relatively untouched continent when it comes to mineral resources. Many large mining houses are showing a bigger interest in Africa than before and South African project companies are also showing a greater interest in African projects. by Trevor Arlington – Project Manager at Fluor South Africa (Pty) Limited

Transparency You Can See Average circulation (Q3 July – Sept 2015) 3 628

Chemical Technology is endorsed by The South African Institution of Chemical Engineers

31 Focus on minerals processing and metallurgy

9 Focus on nanotechnology

PETROCHEMICALS 10 Optimising quill and injector performance in refinery operations

and the Southern African Association of Energy Efficiency

There are dozens of operations in refineries where quills and injectors are used. Before we discuss usage and performance optimisation, let’s clarify the difference between a quill and an injector. The terms are often used interchangeably even though the devices are quite different. by Dan Vidusek and Chuck Munro, both of Spraying Systems Co, Wheaton, Illinois, USA

DISCLAIMER The views expressed in this journal are not neces- sarily those of the editor or the publisher. Generic images courtesy of www.shutterstock.com

17 Focus on petrochemicals

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Chemical Technology • October 2015

http://www.chemicaltechnologymagazine.co.za/

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Chemical Technology • November 2015

COMMENT

An assessment of eight African universities

by Fred M Hayward, Senior Higher Education Advisor, University of Massachusetts, Amherst, USA

A recently published book, edited by Nico Cloete, Peter Maassen and Tracy Bailey, entitled ‘An assessment of eight frican universities: Contradictory functions, knowledge production and pacts’ was built around a research project of the Higher Educa- tion Research and Advocacy Network in Africa (HERANA) and includes data from eight uni- versities, being the Universities of Botswana, Cape Town, Dar es Salaam, EduardoMondlane, Ghana, Makerere, Mauritius and Nairobi. This book is an attempt to provide a data- driven analysis using performance indicators of the eight institutions selected as comparable ‘flagship’ institutions, with the aim of assess- ing their success as knowledge-producing and research-intensive institutions in the age of the knowledge economy. The authors assess the eight institutions based on a set of eight measurable goals and targets: enrolments in science and technology, strong master’s and doctoral enrolments but with a majority of undergraduates, a high pro- portion of permanent academic staff in senior ranks, well-qualified senior staff, low student to academics ratios, high outputs of graduates in SET fields, high outputs of master’s and doctoral degrees, and high levels of new knowledge pro- duction. Only the University of Cape Townmeets all the targets; the Universities of Mauritius, Dar es Salaam and Makerere come close. At the same time the authors explore the contradictory functions and pressures on these institutions – on the one hand, the pressure to produce knowledge useful to national develop- ment, and on the other hand, the contradictory pressures of, to name just a few, public service, outside jobs, growing enrolments, pressure on teaching loads, lack of research funding and the growth of fee-paying students. The chapter on research universities makes the case for the importance of research univer- sities – but shows that, in the main, these are not strengthening their knowledge-generating capacity and are failing to make a substantive contribution to new knowledge generation.

Nonetheless, pointing out that the universities are virtually the only producers of knowledge in Africa and, since higher education institu- tions remain the best, and usually, the only, institutions capable of knowledge production in Africa, the authors underline the importance of efforts to revitalise higher education, especially research and knowledge production functions. The excellent chapter, ‘Academic incentives for knowledge production’, is particularly poi- gnant, contrasting as it does, the incentives in South Africa for publications, with the situations inMozambique, Kenya and, to some extent, the rest of Africa. It describes the commercialisa- tion of the university and the ways in which a combination of low salaries, lack of support, and donor foci have "undermined the possibility of establishing a research culture". The authors note that other than in South Africa there is little by way of financial incentive for research – that the major incentive is the drive for knowledge production. The findings emphasise the lack of connec- tion between research institutions in Africa, stronger connections often being with research partners abroad. This is not surprising given the disparities of research support, but it is disheart- ening, given the years of efforts to promote re- search linkages between African institutions by foundations, theWorld Bank and other funders. In conclusion, the authors stress the need for research-intensive universities – at least one in each country – pointing out that only three universities focus their plans on economic devel- opment – Makerere, Botswana and Mauritius. They also emphasise the critical importance of differentiation, for focused work and to limit costs, as well as for system level recognition of the need to develop research generally. This comment is based on a book review by Dr Hayward which appeared in the South African Journal of Science, Volume 111, Number 9/10, September/October 2015. The full review may be accessed at http://dx.doi. org/10.17159/ sajs.2015/a0120

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Chemical Technology • November 2015

Optimising chemical plant efficiency Technologically advanced instruments can hold the key to boosting productivity

Chemical plants seeking improvements in productivity and efficiency mostly find that the fastest and most cost-effective manner to reach their goal is through the installation and modernisation of process automation systems and advanced field instruments.

I n this manner precise data can be gathered and used to ensure that the plant is optimised and runs like clockwork. These systems also provide more accu- rate forms of measurement for maintenance scheduling and can be employed to introduce preventative main- tenance schedules to guard against failure of critical equipment to ensure production remains uninterrupted. In South Africa one of the oldest and most reliable sup- pliers of broad-based automation and field instrumentation solutions is Linbro Park-based, Protea Automation Systems, which was established nearly 70 years ago to facilitate the measurement and control of production processes across a wide range of industries. Since then the company has grown to become a Level 1 BBBEE supplier and a leader in its field, with long-standing agency agreements with many of the world’s leading instrumentation manufacturers. Incremental improvements According to Jerry Smits, national sales manager for Protea Automation Solutions, the company is able to provide unique process solutions based on its product offerings from any of its manufacturers. In the world of process automation and instrumentation these read like the who’s who of the industry, including well-known brands such as Ashcroft, Land Infrared and Combustion, Moistech, Galvanic, Meriam, Steinfurth, not forgetting Protea’s new German imported house brand, Graphic recorders, temperature transmitters and indicators. “While we may be the sole agents for many of the world’s best known brands in instrumentation, our focus remains

strongly on adding value to our customers by way of resolv- ing problems and providing technical assistance backed up by a wide range of engineering service. We also show customers ways of improving their processes with the use of technology and different configurations of instrumentation in order to achieve their production goals. “Our sales and technical staff are well qualified and each one has extensive on-plant experience which allows them to understand the dynamics of plants and processes when working with clients. This puts them in a position to provide expert opinions and find solutions that meet the needs of each of our clients. To remain at the forefront of technology they also receive regular technology and product-specific training at overseas manufacturers which ensure that our staff are always ahead of the curve when proving technol- ogy solutions.” Full service offering Protea Automation Solutions is an ISO 9001:2008 accred- ited company and has a long pedigree in the world of elec- tronics. It is part of the Protea Technology group, which has played a significant part in building the continent’s industrial automation, mobile communications and broadcasting infrastructure. By supplying world-class hardware and soft- ware solutions, the company has also managed to assist local industries to remain competitive on a global stage. Due to its inward focus on engineering expertise, the company has, until recently, remained one of the coun- try’s best kept secrets in terms of its ability to design and provide appropriate systems for all manner of specialised

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Chemical Technology • November 2015

PETROCHEMICALS COVER STORY

Protea Automation Solutions staff outside the company’s Linbro Park head office.

applications. Through two separate operations, Protea Electronics and Protea Automation Solutions, the company provides far-ranging technologies for a wide range of indus- tries and applications. Group CEO, Gary Johnston, explains that technology drives almost every aspect of the economy today and every business and individual in the country benefits through Protea Technology systems in hundreds of ways. “Our automation systems, for example, provide chemical indus- tries and manufacturers with a means of mechanising and automating systems to both keep up with demands, and to “Beyond the chemical industry, we also supply advanced systems to other engineering intensive industries such as broadcasting and wireless telecommunications. This technology is pivotal to clear communications and actually enables television and radio broadcasts to be sent and received throughout the country. “Similarly, our advanced mobile telecommunications equipment is used by all the major cellular telecommuni- cations companies and ensures reliable coverage of the country. Our optimisation and test equipment also ensures that signal coverage can be measured and that the correct frequencies are being used,” Gary says. For more information contact Protea Automation Solutions, Jerry Smits, on tel: +27 11 719 5700; fax: +27 11 440 9312; email: jerrys@protea.co.za, or go to www.protea.co.za. produce consistent quality products.” Technology for the people

Sean Symons, Technical repair and support, Protea Automation Solutions.

Environmental concerns Due to increasing pressure on the environment and the need to protect it Protea Automation Solutions has sourced a wide range of analytical systems for process analysis. Systems include portable, in-situ and extractive systems to analyse anything from nitrification and turbidity, to toxic gases, flue gas temperature and velocity, among others.

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Chemical Technology • November 2015

Blurring the lines between nanotech and biochemistry

by Gavin Chait

The walls, they no longer bounce the way they used to. When I was younger, I would launch myself at them, flinging myself across the court to reach the squash ball, ricocheting off them to reach the next shot.

N ow. The walls are harder. Much less forgiving. I realised the steady progression of time and bone-damage when I leapt, achieving a horizontal position one metre above the floor, and concluded – while still up there – that this was not going to end well. It didn’t. Doctors say I should, eventually, be breathing unaided once more. Playing the cello, they apologise, is out of reach. Good thing, I never tried it before. But still, there must be something we can do about all this lack of dexterity and volatility that comes with ageing. Let’s start with all those muscle and joint injuries and get more intimate from there. My knees could definitely do with what Korean Scien- tists at the Center for Nanoparticle Research, Institute for Basic Science (IBS) have come up with. They have created a ‘fabric’ made of ~150 nm diameter silver nanowires in an interlocking coil, and embedded in elastic material. This conductive fabric can be linked up to a small battery and provides direct heating over and around the joint. Better still, because it is light-weight, wearable, and breathable, it can be worn while running around. This is great news for squash players and those heading to the Arctic to climb mountains, or something. The question is going to be how durable such thin silver wires can be under stress, and I imagine this goes under the heading ‘needs work’. Silver, in my experience, has a tendency to break rather easily. However, beyond all the hype of nanotechnology in circuitry or providing weird properties, this is a fairly simple implementation with direct applications. It’s a wonder it hasn’t come sooner. Nanowire devices have been around for a while. Think

coronary stents. But these are now being used in more subtle ways. For example, a medical team from the Wyss Institute at Harvard University and the New England Center for Stroke Research at University of Massachusetts, have de- veloped a technique to re-vascularise (ie, restore bloodflow) to a vessel obstructed by a clot. They use an intra-arterial stent to open a channel through the clot and then inject a nanotherapeutic. “What’s progressive about this approach is that the temporary opening of a tiny hole in the clot — using a stent device that is already commonly used clinically — results in a local rise in mechanical forces that activate the nano- therapeutic to deploy the clot-busting drug precisely where it can best do its job,” says Donald Ingber, Wyss Institute Founding Director. And bone repair is being speeded up with 3D bioprint- ing which mixes biocompatible gels with stem cells and active proteins. This is where things take an odd turn.  When we think of nanomaterials, we (I) tend to think of things that are – in some way – manufactured. It may be chemically, like nanotubes microprocessors, or even machined. The active agent in such production is, though, human. What happens when we use actual living organisms to manufacture novel nanomaterials and tools? Is that biotech or nanotech? Engineering or biology? It doesn’t necessarily matter philosophically, but there are practical implications. Back in 1986, Eric Drexler imag- ined a classic end-of-the-world tale in “Engines of Creation”: “Imagine such a replicator floating in a bottle of chemicals,

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Chemical Technology • November 2015

NANOTECHNOLOGY

that their thread was strong, but nevertheless significantly weaker than a spider’s.” Spiber are partnering with North Face to produce The Moon Parka, a product that is to go on tour later this year and which you may be permitted to buy in 2017. I do like the idea of spider-silk clothing. But imagine the same material used to repair injuries? It should be as bio- compatible as silk. “It’s hard to see unless you look closely, but this is the beginning of biological nanotechnology. These are some of the very first deliberately designed biological molecules to make it into a non-pharmaceutical market. Technologically, the silks in these fabrics are made of designed components an order of magnitude smaller than Intel’s best transistors. And (under biological conditions) are significantly more functionally versatile,” says toufka , also on Hacker News. Yes, and that’s the grey goo problem. Since the machines are actual living organisms, they might be able to reproduce outside of the factory. Spider silk fabric is nice. Spider silk clogging up our waterways, or being excreted as waste by some infectious illness; not so nice. And yes, we’re definitely on the cusp of something incred- ible which will change our experience of healthcare, as well as the world in which we live. As the nanomachines we want to build, or the scale of action we wish to take, shrinks and becomes more complex, we are definitely going to find it easier to work with genetically engineered organisms who will build things for us. We’re looking at nanomaterials which need to be deliv- ered as a payload to a specific activation site in the body, without triggering an immune response or getting lost. We

making copies of itself…the first replicator assembles a copy in one thousand seconds, the two replicators then build two more in the next thousand seconds, the four build another four, and the eight build another eight. At the end of ten hours, there are not thirty-six new replicators, but over 68 billion. In less than a day, they would weigh a ton; in less than two days, they would outweigh the Earth; in another four hours, they would exceed the mass of the Sun and all the planets combined— if the bottle of chemicals hadn’t run dry long before.” This doomsday “grey goo” would – wait for it – wait for it – threaten life on earth. On the other hand, Spiber, a Japanese company, has just developed the first artificial spider silk fibre which they’re called Qmonos. The fibre is produced during a fermenta- tion process led by genetically engineered yeast producing recombinant proteins. They spent 11 years on this, using 656 gene synthesis designs. It turns out, however, that you can’t just make the pro- teins and expect proper silk to result. As dre85 notes on Hacker News, “… expressing the proteins is the easy part. Spinning the proteins into a thread was the tough part. Ap- parently spiders have special excretion structures/organs that can anneal the proteins to the right conformation ex- tremely quickly as they are ejected. This is why a spider can basically just jump off of anything and shoot out his ‘bungee cord’ while falling which is incredibly fast if you think about it. When the researchers tried to replicate this by simply shooting the concentrated protein solution through a tiny capillary they weren’t able to achieve the same molecular structure for their thread nor at the same speed. They noted

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Chemical Technology • November 2015

NANOTECHNOLOGY

A video you can watch on Vimeo called ‘Biologic’ by the Tangible Media Group demonstrates work by MIT on hygro- morphic transformation. These are ‘devices’ using bacteria which respond to humidity by expanding. They use this to create fabric that curls in response to heat and humidity. As two dancers perform, their clothes automatically respond to their sweat by opening up baffles to create vents. Later, one of them drops a teabag into hot water, which automatically signals once the bag is ready to be removed. I’m not sure that having automatic vents will improve my squash, but I’m looking forward to the spider-silk shoes, heating bands around my knees, and nanomaterials in my circulation preventing me from going into cardiac arrest. And maybe, one day, the walls will even bounce – just a little – when they see me coming.

want to strengthen ailing muscles, rebuild degraded carti- lage, and regenerate cardiac cells following heart attacks. On 27 October this year, the US Food and Drug Admin- istration approved a genetically engineered virus called talimogene laherparepvec (T-VEC) to treat advanced melanoma. Only four days earlier, the European Medicines Agency also came out in favour (although has not yet ap- proved it). This is the first oncolytic virus which preferentially infects cancer cells, killing them. Viruses are still highly conten- tious in terms of debating whether they’re living things or just highly sophisticated machines. And here we’ve designed one to fight one of the developed world’s most terrible scourges. In China, where drug trials are a little less well-scrutinised, an entire medical tourism industry has developed with people unable to get this type of therapy at home heading there for onco-virus treatment. Used in combination with other therapies, these viruses improve survival rates and are able to target systemic can- cer that has spread beyond its main site. It isn’t yet a cure, but the potential is one of the most exciting things in oncol- ogy in years. And a virus that escapes its lab and kills cancer is probably bad for doomsday scenarios since that sounds like good news for everyone but the pharma companies. And then there’ll be the stranger things. Stuff that will make you feel particularly old in 20 years’ time amongst kids just ‘out of the cradle’ who will grow up with it, just like the latest generation has with mobile phones.

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Chemical Technology • November 2015

Advance could bring commercial applications for silver nanowires Silver nanowires hold promise for applica- tions such as flexible displays and solar cells, but their susceptibility to damage fromhighly energetic UV radiation and harsh environmental conditions has limited their commercialisation.

New research suggests wrapping the nanowires with an ultrathin layer of carbon called graphene protects the structures from damage and could represent a key to realising their commercial potential. “We show that even if you have only a one-atom-thickness material, it can protect from an enormous amount of UV radiation damage,” said Gary Cheng, an associ- ate professor of industrial engineering at Purdue University in Indiana, USA. Devices made from silver nanowires and graphene could find uses in solar cells, flex- ible displays for computers and consumer electronics, and future ‘optoelectronic’ circuits for sensors and information process- ing. The material is flexible and transparent, yet electrically conductive, and is a potential replacement for indium tin oxide, or ITO. Industry is seeking alternatives to ITO because of drawbacks. It is relatively expen- sive due to limited abundance of indium, and it is inflexible and degrades over time, becoming brittle and hindering perfor- mance, said Suprem Das, a former Purdue doctoral student and now a postdoctoral researcher at Iowa State University and The Ames Laboratory. However, a major factor limiting commer- cial applications for silver nanowires is their susceptibility to harsh environments and electromagnetic waves. “Radiation damage is widespread,” said Das, who led the work with Purdue doctoral student Qiong Nian.

FOCUS ON NANOTECHNOLOGY

“The damage occurs in medical imaging, in space applications and just from long-term exposure to sunlight, but we are now see- ing that if you wrap silver nanowires with graphene you can overcome this problem.” Findings appeared in October in the jour- nal ‘ACS Nano’, published by the American Chemical Society. The paper was authored by Das; Nian; graduate students Mojib Saei, Shengyu Jin and Doosan Back; previous postdoctoral research associate Prashant Kumar; David B Janes, a professor of electri- cal and computer engineering; Muhammad A Alam, the Jai N Gupta Professor of Electri- cal and Computer Engineering; and Cheng. Raman spectroscopy was performed by the Purdue Department of Physics and Astronomy. Findings showed the graphene sheathing protected the nanowires even while being subjected to 2,5 MW of energy intensity per cm² from a high-energy laser, which vaporises the unwrapped wires. The unwrapped wires were damaged with an energy intensity as little as 0,8 MW per cm². (The paper is available at http://pubs.acs. org/doi/abs/10.1021/acsnano.5b04628.) “It appears the graphene coating extracts

and spreads thermal energy away from the nanowires,” Das said. The graphene also helps to prevent moisture damage. The research is a continuation of previ- ous findings published in 2013 and detailed in this paper: http://onlinelibrary.wiley. com/doi/10.1002/adfm.201300124/full. The work is ongoing and is supported by the National Science Foundation and a National Research Council Senior Research Associateship. lower images depict how graphene sheath- ing protects the nanowires even while being subjected to 2,5 MW of energy intensity per cm² from a high-energy laser, an intensity that vapo- rises the unwrapped wires. The upper images depict how the unwrapped wires are damaged with an energy intensity as little as 0,8 MW per cm² . (Purdue University photo) New research shows wrapping silver nanowires, which are promising for applications such as flexible displays and solar cells, with an ultrathin layer of carbon called graphene protects the structures from damage and could represent a key to realizing their commercial potential. The

Story by Emil Venere, 765-494-4709, venere@purdue.edu.

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Chemical Technology • November 2015

Optimising quill and injector performance in refinery operations by Dan Vidusek and Chuck Munro, both of Spraying Systems Co, Wheaton, Illinois, USA

There are dozens of operations in refineries where quills and injectors are used. Before discussing usage and performance optimisation, let’s clarify the difference between a quill and an injector. The terms are often used interchangeably even though the devices are quite different.

A n injector has one or more spray nozzles on a pipe and delivers a specific volume of fluid at a speci- fied pressure drop. (See Figure 1.) The nozzle(s) convert fluid into a predictable drop size spectrum and provide specific spray characteristics. The use of spray nozzles allows more control over the distribution of the injected liquid into the receiving process fluid. A quill is a pipe with slots or holes. (See Figure 2.) The injected fluid flow is uninhibited. The receiving process

show the performance advantages of injectors over quills. If you are cooling a gas, it is critical to know drop size since it is proportional to how fast the cooling will be achieved and when drop evaporation will occur. If droplets are too large, you may not achieve the desired cooling effect. This can result in excess fluid in the pipe or duct, cause maintenance problems and damage downstream equipment. Chemical injection requires a greater surface area of injected liquid. Greater surface area requires better gas- to-liquid (or liquid-to-liquid) interaction to ensure efficient heat or mass transfer. A third example is water wash. The wash water, via surface area contact, must have sufficient interaction with the vapour stream in order to dilute the corrosives and dis- solve any water-soluble materials present. An injector with a spray nozzle provides more efficient mixing and better drop size breakup than a quill and can provide more con- trol over the process – something a quill cannot achieve. Injectors cost more than quills. However, given the long

stream breaks up and mixes the injected fluid. Injectors and quills: what’s the difference? Should you use a quill or an injector?

The answer is somewhat dependent on your operation but, in general, you should use an injector unless you don’t need any control over spray characteristics such as flow rate, drop size or spray pattern. The most common uses for quills and injectors are in gas conditioning, chemical injection and water wash. Here are a few examples that

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Chemical Technology • November 2015

PETROCHEMICALS

Figure 1: Injector with spray nozzle

Figure 2: Quill with slot

and a gas flow through air atomising nozzles. Air atomising nozzles are often called dual fluid nozzles. Spray nozzles are designed to produce a spray pattern: full cone, hollow cone or flat spray. Full cone sprays are formed by swirling the fluid inside the nozzle by a stationary vane. The maximum free passage in full cone nozzles is a bit limited due to the vane design, so it is important to keep in mind that clogging could be a problem when using liquids with suspended particulates. If there are particulates in the fluid, consider using full cone spray nozzles featuring a maximum free passage design.

service life requirements of injectors and quills – up to 10 years – the cost differential between the two is insignificant should a problem occur due to imprecise flow. The cost of unscheduled downtime, damage to downstream equipment or incomplete cooling, washing or chemical reactions, will greatly exceed the price differential between a quill and an injector. What you need to know about injector spray nozzles Spray nozzles fall into two categories: hydraulic or air atomis- ing. A single liquid flows through a hydraulic nozzle. A liquid

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Chemical Technology • November 2015

Figure 3: Typical uses of full cone sprays: overhead water wash, defoaming, torch oil injectors and vacuum tower spray distributors.

Figure 4: Typical uses of hollow cone sprays: flue gas cooling and urea injection for SNCR NOx control, desuperheating, quenching and water wash.

Hollow cone sprays are formed by injecting a stream of fluid tangentially into a swirling chamber. The swirling action allows a uniform film of liquid to discharge from the nozzle forming a ring of fluid. Droplets are relatively uniform in size throughout the spray. Hollow cone spray nozzles have a large free passage so the risk of clogging is minimal. Flat spray nozzles use an elliptical orifice to create a flat fan spray pattern. The exact shape of the orifice determines the spray angle which can range from a solid stream to a

120° spray angle. Drop size is medium – smaller than full cone sprays and larger than hollow cone sprays. Air atomising nozzles are available in a wide range of spray patterns – hollow cone, full cone and flat spray. Although available as internal or external mix nozzles, injectors in refinery operations are generally equipped with internal mix nozzles. Internal mix dual fluid nozzles produce the smallest droplets. The liquid and gas streams in dual fluid nozzles are typically kept separate until the two fluids are brought together just behind the discharge orifice. This enables mix- ing efficiency to be maximised and the smallest possible drop to be produced. If the two fluids are mixed earlier, coalescence and drag would increase drop size. Air atomising spray nozzles designed for operation at low flow rates – 2 to 5 gallons per minute (8 to 19 litres per minute) – can be sensitive to operational pressures. When a high volume of liquid needs to be atomised – like 25 to 50 gallons per minute (95 to 189 litres per minute) – large quantities of gas are required to achieve small droplets. One more selection consideration is the environment where the nozzle will spray. For nozzles to atomise, they need to spray into vapour. Atomisation does not occur when liquids are sprayed into liquids. Spray nozzles with multiple orifices may prove advantageous. Determining spray direction There are two ways to spray: co-current or counter-current. Each approach has advantages and disadvantages. Table

Table 1: Spray direction pros and cons

CO-CURRENT SPRAYING

COUNTER-CUR- RENT SPRAYING

More flexibility in where the injector is placed in the pipe Injector must be placed in the center of the pipe Bearding (build-up) on the nozzles is minimized because the nozzle is spraying in the same direction as the process stream Bearding on the injector can occur if there is a high amount of particulate in the process stream. The build-up can increase stress on the injector Impingement on pipe walls possible if injector is not placed in center of process stream Larger droplets created by fallback of sprayed droplets coalescing with newly sprayed droplets

Longer residence time of spray by opening up the spray pattern; shearing of the droplets can result in smaller droplets

Faster reaction time required for full evaporation of the injected fluid

Table 2: Effects of nozzle type and orientation on performance

NOZZLE TYPE

SPRAY DIRECTION INJECTOR MEAN DROPLET DIA. D V0.5 (MICRONS)

% CONTACT WITH PIPE WALL OUTLET

% WATER EVAPORATED

OUTLET MEAN DROPLET DIA. DV0.5 (MICRONS)

TEMPERATURE

Hollow cone / large droplets Co-current

1115μ

85 %

480°F (249°C)

4%

428μ

Hollow cone / small droplets Co-current

95μ

0.40 %

349°F (176°C)

58%

133μ

Hollow cone / small droplets Counter-current

95μ

2.0 %

283°F (139°C)

78%

67μ

Initial Process Stream Temperature = 540°F (282°C). Pipe Diameter = 36 inch (914 mm). All measurements downstream from injector are at 15 feet (4.6 m) – 5 pipe diameters

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Chemical Technology • November 2015

PETROCHEMICALS

Figure 5: Typical uses: steam quench, desuperheating, torch oil injec- tors and catalyst reforming cooling.

Figure 6: Typical uses: gas cooling, fresh feed injectors to FCC units, emergency quench and urea injection for NOx.

FSI Model

CFD Model

Injector design considerations Injector design and construction must be carefully planned and validated. Pressure, temperature, corrosion and erosion typically determine process code requirements. Material options include stainless steel, HASTELLOY ® , INCONEL ® and titanium. Using computer modelling to validate injector design and performance is generally recommended. A failure inside the process pipe is dangerous and it is more costly than using computer modelling to validate the system design before it is finalised and installed. The second way of modelling is used to validate injector performance with Computational Fluid Dynamics (CFD) models. These models predict the interaction of the injected fluids with other fluids or a vapour and determine the heat transfer, mass transfer, chemical reactions and other flow- related phenomena that will occur when the fluids interact under specific conditions. Minimising maintenance downtime Injectors may need to be removed for inspection, routine Figure 8: Using computer modelling enables injector design and per- formance to be validated prior to construction and prevents costly and potentially dangerous design problems.

Figure 7: The placement of an injector in a pipe can significantly impact performance.

1 summarises the pros and cons of each approach. A common rule of thumb is to centre the injector in the process pipe and spray co-currently. However, this doesn’t always produce the best results. See Table 2. This example illustrates how the type of spray nozzle used and the orientation of it can affect performance. When the first and second spray nozzles in Table 2 are compared, the impact of using a properly sized spray nozzle becomes clear. Wall wetting is decreased, the amount of water evaporated is increased and droplet size is smaller at the end of the pipe. The third spray nozzle in the chart is the same as the second nozzle but it is spraying counter-current to the va- pour stream. There is a slight increase in water contact with the wall as the spray plume opens up. However, a greater amount of water evaporation occurs and droplet size is even smaller at the end of the pipe. Which is the better spray direction? In this case, the ap- plication requirements will determine if 2 % water contact with the wall is acceptable to achieve greater evaporation and cooling.

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Chemical Technology • November 2015

PETROCHEMICALS

Figure 9: Mechanical retractable injector

Summary The guidelines outlined here provide a good starting point when a new or replacement injector is required. However, the specifics of your operation will determine what’s neces- sary to optimise performance. You may find the following checklist helpful as you move forward with your next injector project: 1. Don’t automatically replace like with like. Revisit the current design. 2. Be meticulous about the details and eliminate open issues. Use modelling to uncover potential problems. 3. Consult with experts even if you are confident in your specifications/design.

maintenance or insertion in another location. Safely retract- ing the injector so an isolation valve can be closed prior to unbolting the injector from the process pipe is a major advantage. There are two types of retractable injectors. One is removed manually and the other features a handwheel and screw. Using retractable injectors can also help reduce down- time dramatically. One refinery in the midwestern United States is using mechanical retractable injectors to spray liquid nitrogen into the hydrocracker reactor to cool the catalyst prior to replacement. The injectors are inserted and the cooling process begins while the plant is on line.

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Chemical Technology • November 2015

Reliable Flow Measurement.

Proline Promass 200

Combining the benefits of the Promass measuring performance with two-wire technology no longer requires compromises. The Promass 200 can be integrated into existing plant systems seamlessly and without added effort. Promass 200 creates new benchmarks in relation to safety and uniformity in flow measurement: • two-wire technology  Efficient (4-20mA) from the measuring point to the control room (PLC, DCS)

•  Developed for SIL 2/3 applications •  Suitable for use in safety systems •  Internationally recognised hazardous area approvals •  High measuring performance for continuous process control •  Reduced costs for installation and wiring •  Seamless integration into existinig infrastructures •  Common installation practice

Endress+Hauser (Pty) Ltd Phone Fax info@za.endress.com www.za.endress.com +27 11 262 8000 +27 11 262 8062

FOCUS ON PETROCHEMICALS

Intrinsic safety – Highest operational safety around the clock

Process monitoring is becoming more demand- ing and the need for maximum product quality is steadily increasing. This is why Endress+Hauser South Africa continues to provide industry-specific flow measurement solutions optimised for future technology requirements. The com-

pany’s new generation of Proline flowmeters is based on a uniform device concept. This means time and cost savings, as well as max- imum safety over the entire plant life cycle. In the chemical pro- cess industry, Coriolis flowmeters have been

used for decades with great success. This is in no way astonishing, be-

cause this measurement technology has unique advantages in comparison to other methods: • Independent of physical fluid properties such as conductivity, pressure, temperature, density or viscosity • One-of-a-kind multi-functionality – simultaneous measurement of

mass flow, volume flow, density and temperature • Maintenance-free devices without moving parts • No inlet and outlet runs required • Operable flow range of up to 1 000:1

• Insensitive to external process influences such as pipe vibrations • High field accuracy, even with greatly fluctuating process and ambient conditions. Proline is a proven and uniform product concept, designed to do the same things the same way, thereby increasing the safety and efficiency of your operations. The Human Machine Interface (HMI) and subsequent device set-up and programming are extremely user- friendly. This ensures that the process can be securely controlled with confidence and can be integrated seamlessly into the plant asset management, providing reliable information for optimising production and business processes. The Promass 200 has been developed for SIL2/3 applications and has internationally recognised Ex approval, including the local South African requirements. Round-the-clock operational safety and plant availability are particularly important in the chemical and petrochemical industries. The Promass 200 consistently ensures this higher safety and thereby enables lower operating costs. In addition, plants have to be oper- ated as cost-effectively as possible over the years so as to attain high performance and availability. The complexity involved, whether in the process or in utilities, can only be managed by uniform and standardised field instrumentation. Promass 200 is the perfect solu- tion for exactly such areas of application. As a true two-wire device, the Promass 200 can be integrated into existing plant systems to provide the following: • High operational safety in Ex areas due to the intrinsically safe design (Ex ia)

Festo provides ideal and reliable solutions with maximum process safety for all sectors, be it petrochemicals , basic chemicals or fine and specialty chemicals . Control cabinets for the chemical industry

Tel: 08600 FESTO (33786) Email: sales@za.festo.com Branches nationwide. www.festo.co.za

• Reduce cost for installation and wiring • Seamless system integration and wiring. • Common installation practice.

For more information contact Frans van den Berg on tel: +27 11 262 8000, or email info@za.endress.com.

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Chemical Technology • November 2015

Fuel price is down – but how is the national price determined?

South Africa consumes on average more than two-billion litres of fuel per month. The pump price is therefore a contentious issue for the majority of individuals and busi- nesses, whose finances are directly affected by cost fluctuations. The fuel price is also an issue where the vast majority of the diverse population is united in opinion – welcoming price cuts, while resenting price hikes. This resentment is understandable, es- pecially if the public is not communicated to in a transparent manner. Afric Oil CEO Tseke Nkadimeng states that petrol prices have been regulated since the 1950s to ensure economic viability for the industry. “The na- tional fuel pricing model is, however, defined by industry jargon that leaves the public unsure of where their money is being spent.” According to Nkadimeng, the two most prominent variables in determining the fuel price are the US$ price of crude oil, and the Rand’s performance against the Dollar.

FOCUS ON

PETROCHEMICALS

The cost of freight is also priced in US$, and exchange rates once again play a central role,” he continues. These costs can be further compounded by demurrage, which is the penalty costs incurred by ships delayed in foreign ports. What’s more, the cargo must also be insured when in transit. This is calculated at 0,15 % of the fuel value and freight costs. “This is a reasonably fixed cost and should not fluctuate much month-to- month, however, millions of litres are transported on each ship – making the cost quite substantial, especially with a weaker Rand,” says Nkadimeng. Once these international costs have been dealt with, Nkadimeng reveals that local costs are enforced too. “Cargo dues are the costs associated with offloading the cargo at the harbour. The fuel is then held in coastal storage facilities, which charge around 2 c/ℓ per day with a maximum of 25 days storage. The cost of financial transactions and credit facilities also needs to be covered through stock financing, which is based on the landed cost values of refined petroleum, 25 days stock holding and prime interest rate minus two percent,” he explains. Government taxes and levies constitute up to 50 % of the fuel retail price. Other factors that determine the fuel price are the wholesale margin that distributors are allowed to add to the wholesale price. This currently stands at 64 c/ℓ. The next is the dealer margin, which currently stands at 155 c/ℓ. These margins are adjusted annually and approved by the Minister of Energy. It may seem unfair, at face value, that wholesalers and retailers are entitled to add a total of R2, 19 per litre to the price of fuel for their ‘gain’. Nkadimeng stresses that these margins are in fact extremely low, and there is very little room for negotiations. “It is important to bear in mind that these margins do not go straight into the pockets of wholesalers and retailers.” “Most people learn the newly-adjusted price of petrol a few days before the Department of Energy makes the official announcement. In my opinion, more focus should be placed on the predicted future pump price of petrol from various news outlets – which regularly give the price and gold and crude oil, but the indicative price of petrol is far more important to the average South African.”

“Naturally, when oil prices rise and fall, so too does the petrol price. Exchange rate performance is also a major contributor, and the Rand’s poor performance in recent months is indicative of the higher fuel prices.” Nkadimeng indicates that freight costs are also a determining factor. “Most of South Africa’s fuel is imported by ship from the Arab Gulf region. Approximately 20 percent of this amount is already refined, while the balance is refined at coastal and inland depots.

For more information contact Tseke Nkadimeng on tel +27 11 911 4280/4, email: info@africoil.co.za or go to www.africoil.co.za.

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Chemical Technology • November 2015

Reduce VOCs with oil and gas storage covers

From the sky, Greatario Covers’ new oil and gas tank covers look just like any tank cover. In reality, the Crude Oil Vapour Emission Reduc- tion System (COVERS) is a series of hexagonal shapes with symmetric ribs on both sides that allow the floating structures to form an interconnecting blanket barrier at the surface of the heavy oil. The unique floating cover system – targeted at hot, heavy-duty oil and gas storage applica- tions – reduces greenhouse gas (GHG) emis- sions and water vapour that acts as a carrier of VOCs and harmful carcinogenic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene, according to Greatario. Tomake those lightweight shapes, Greatario Covers used DuPont™ Zytel ® LCPA long chain polyamide resin for its superior chemical resis- tance and low moisture absorption, compared to competing thermoplastics like polyolefin. “The high-performance capabilities of Zy- tel ® LCPA resin has enabled us to penetrate highly aggressive oil and gas applications that were beyond the reach of previous materials,” said Terry Frank, vice president of sales for Canadian-based Greatario Covers. Zytel ® LCPA resin is chemically compatible with heavy oil components up to temperatures of 100 °C. It is also resistant to thermal shock with testing completed at -40 °C to 100 °C for sudden rapid temperature exposure. The low water absorption of Zytel ® LCPA resin avoids weight gain that would affect the Save money with WearCheck For any business that relies on machinery with moving components, a substantial, and critical, investment, are the fuels, lubricants, air and coolants (F.L.A.C) which help maintain compo- nents in peak operating condition. Without proper on-site management of FLAC, there is a direct link to the detrimental effect on overall machine / component health. An ongoing situation like this can lead to premature component failure, which is very costly and unproductive, and can cripple a business. Conditionmonitoring specialists WearCheck have developed a FLAC management system, which falls under the umbrella of WearCheck’s LubriGard programme, and which is geared to assist plant owners to reduce maintenance and operating costs without compromising the equipment in any way.   Chris Hattingh (operations/ technical sup- port for WearCheck), elaborates; ‘FLAC audits establish the current conditions and the man- agement of FLAC, problems are identified, and an action plan for improvement is mapped out. ‘Recommendations are made to achieve industry or equipment OEM standards for lube

flotation of the Hexa-Cover ® Floating Cover and its capability to trap vapours. The thermoplastic floating cover, measuring 21,59 cmby 18,79 cm by 8,38 cm, maintains its hexagonal shape to ensure the tiles will interlock uniformly on the oil’s surface. The reduction in absorption minimises the need for ventilation and reduces odour release and product evaporation, thus of- fering environmental benefits and reduced cost. Along with its exceptional chemical resis- tance, low moisture absorption and excellent thermal stability, Zytel ® LCPA resin delivers an- ti-static capabilities and corrosion resistance. For more information contact Carole Davies on tel +1 248-583-8112 or email carole.a.davies@dupont.com. Greatario Covers utilised DuPont™ Zytel ® LCPA long chain polyamide resin in the company’s Hexa-Cover ® Floating Cover. (Photo courtesy of Greatario Covers) and fuel cleanliness. Studies reveal contamina- tion as a major cause of premature failures – in fact, as much as 70% of all failures are due to the contamination culprit. ‘Once bulk storage and handling are assessed, we inspect the equipment. After- market products assist us in further improving the quality of fuel and lube cleanliness levels.’ WearCheck’s FLAC programme has re- corded good results to date. ‘We’ve extended drain intervals on some customers’ sites to 1 000 hours without com- promising equipment health, but they’ve been dedicated to this programme for the past few years.  ‘It is important to note that FLAC is not a quick fix, but rather a maintenance culture change and it takes time.  Also, FLAC and Wear- Check oil analysis results work in tandem― one cannot function without the other.’ For more information contact WearCheck on tel +27 11 392 6322, email support@wearcheck.co.za or www.wearcheck.co.za.

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Chemical Technology • November 2015