Condition monitoring systems provide 30 per cent more cooling tower uptime for power stations.

Medway Power Station in the UK is making significant reductions in downtime due to unexpected failures on the station's induced draft cooling tower.

In particular, the integrated condition monitoring system is enabling engineers to assess the real-time performance and functionality of twelve large diameter cooling fans, together with associated drive motors and gearboxes, and to implement a long-term predictive maintenance strategy that has improved uptime by over 30 per cent and delivered tangible cost savings from these business critical systems.[Page Break]

690MW capacity

Operated by SSE (Scottish and Southern Energy), Medway Power Station is located on the Isle of Grain on the estuary of the River Medway in Kent. The station uses a combined cycle gas turbine, with a capacity of 690MW that enables it to power around 970,000 homes in the region.

The station has a single cooling tower, with twelve individual induced draft cooling cells. Each is fitted with a motor-driven 6m diameter fan, with fibreglass blades, mounted in a cowl at the top of the cell, to enable cool ambient air to be drawn in from the base of the cell and across heated turbine water as it falls through a series of baffles that maximise heat transfer. The drive motors are located on the outside of the cowls and provide power through gearbox units, which are positioned within the body of each cell.[Page Break]

Extreme conidtions

Fans, motors and gearboxes are all subject to extreme conditions. For example, as the site is in an exposed location, high wind speeds and downdrafts can affect fan operation, while the concentration of salt in the atmosphere, combined with dust and particulates from a nearby aggregate plant, cause corrosion and damage to motor and fan units.

Similarly, the position of the gearboxes beneath the fan units means that they are continuously exposed to the flow of water as it is blown down each cell.

Clive Davies, Control and Instrumentation Project Engineer, explains, "The nature of the application means that we have to pay particular attention to regular maintenance, as bearings and seals in drive shafts and fan spindles, in particular, can wear or fail.

In the past, worn bearings on the drive end of gearboxes led to excessive gear wear, reaching the point where gearboxes had to be replaced or removed for overhaul. This is an expensive operation, requiring partial dismantling of a cell, using heavy lifting gear.

A similar situation could occur if fan spindle bearings ran out of alignment, as excessive vibration would eventually lead to de-lamination of the fibreglass blades.

In each instance, it means taking a cooling cell offline, which can affect our generating capacity and thus our revenue earning potential from the National Grid."[Page Break]

Temperature monitoring

Until recently, engineers at Medway Power Station had used hand-held vibration and temperature monitoring devices to check on the condition of the various systems used in each cooling tower cell.

"Although reasonably accurate, this was a time consuming exercise, as motor, gearbox and fan units are difficult to access, and only provided us with historical data; so we only knew about problems when they had occurred or were about to occur," says Clive Davies.

Component repair

To improve the operational efficiency of the power station, SSE embarked on a programme to install a dedicated condition monitoring system for the cooling tower, as part of a longer term predictive maintenance strategy.

The new system is based around the SKF IMx-S online condition monitoring system, connected to a network of 60 accelerometers; there are five of these on each fan, motor and gearbox, plus an SKF Machine Condition Transmitter (MCT) fitted to each gearbox input shaft bearing to provide an alarm trip function.

SKF's on-line monitoring systems provide automated machinery monitoring for up-to-the-minute information to help you optimise the operation of key production assets.

On-line systems complement the use of periodic data collection instruments, facilitating a proactive approach to reliability with round-the-clock monitoring of machinery in harsh, remote, unsafe or difficult to reach locations.

The SKF Multilog On-line System IMx-S is a key component in an advanced condition monitoring system. It is a robust measurement unit designed for tough industrial environments.[Page Break]

Each SKF Multilog IMx-S 16 is equipped with 16 analogue signal inputs, and the SKF Multilog IMx-S 32 with 32 analogue signal inputs.

Outputs are relayed to a control room terminal running the SKF @ptitude monitoring analysis and reporting software, providing a real-time display of all key operating parameters.

Clive Davies praises the support that SSE received from SKF: "They helped us throughout the planning and implementation phase, providing valuable information and practical advice. They also gave us comprehensive training and undertook the installation in a professional and efficient manner; indeed, they have been one of the few outside contractors with an almost perfect on-site safety record - this is an important factor for us as we have a strong health and safety policy that everybody entering the site has to follow."

He concludes: "The new SKF conditioning monitoring system enables us to identify wear in key components long before it becomes a potential problem.[Page Break]

Planned maintennce

As a result, we can plan essential maintenance in advance and for a time when we know that demand for generating capacity will be low.

Just as importantly, we are now seeing significant improvements in availability, typically in the order of 30 per cent, which contribute directly to our ability to maximise the revenue from our power generating plant."

For more information, visit www.skf.com

Femke Schaefer and G Bertels consider results from the Dutch Economic Subsidy Programme concerning innovation and energy.

In recent years, Dutch subsidy policy has been targeted intensively at the theme of innovation and energy via its subsidiary, 'Agentschap NL.' In 2010, the policy was converted into a 'green deal' approach, with the government becoming more indirectly involved. The integration of the themes of energy and innovation has however very much remained the goal of the approach. Subsidies were previously allocated primarily through a 'tender set-up', using a weighted evaluation system; a kind of innovation contest.

In 2005/2006, Bronswerk Heat Transfer reached two top places in this system with its RADIAX-compact pumps, compressors and turbines and the Whizz-Wheel industrial fan projects. Both are innovation-intensive novelties for two energy usage fields which account for around 50 per cent of all electricity worldwide. The potential energy savings for both projects could make a very significant contribution to worldwide CO2 reductions, but will certainly enable an extensive range of equipment relating to heating, cooling and industrial process improvements to function more effectively.

The new fans that were developed with the support of the subsidies consume 50 per cent less energy and are also 6dBA quieter; they are applicable in a wide range of markets. The RADIAX ultra compact compressor can achieve savings of seventy to 80 per cent in heat recovery processes.[Page Break]

Target markets

The target markets for the two energy-saving products and technologies are oil/gas, refrigeration technology, air conditioning, computers (and data centres and servers in particular), domestic appliances, car cooling systems and ventilation, electric motors, and boiler superchargers. Equipment in these markets often needs to last for decades, which is why the markets are often hesitant when it comes to highly innovative technologies: they have to be reliable, long-lasting, and capable of integration with existing equipment.

In the past five years, however, companies have been increasingly active in adopting new technology that saves energy while respecting the environment, all based on a sustainability philosophy.

Another important reason for their doing so is the growing realisation that selectively implementing energy-saving equipment can help deliver a better process economy. For example, an ever-greater number of companies aim to see the costs of their investment repaid within around five years, which amounts to a return on investment of about 20 per cent.

The major energy companies seek to achieve repayment within 10 years (which is still a return of 10 per cent). The support of the government/'Agentschap NL', through energy and environment covenants, creates a stronger platform for the introduction of breakthrough innovations - pioneering technologies that can bring about significant changes in organisations, and for which a strong entrepreneurial and investment-minded company attitude is required.

The business-outlook has become more favourable thanks to this change of policy, but the current uncertain financial climate is markedly making it more difficult to secure financing for projects. However, in many markets there are companies with very healthy cash flows, which are not particularly dependent on banks or their government. Offering customers convincing financial and technological benefits means it is easier for them to make decisions based on sustainability. Even the most conservative markets are now coming round to this well-founded philosophy.[Page Break]

Fan technology

More than two years after the market introduction of the new fans, there has been a worldwide response and intensive interest from the very markets and geographical areas that were not directly approached. The basis for this interest appears to be the outstanding performance of the systems in practice, about which information has now found its way onto the internet.

There is no stopping the worldwide flow of information on the almost unbelievable performance: a 50 per cent reduction in energy consumption, noise levels that are 6dBA lower than the quietest existing fans, in addition to which the fans are much more compact, lighter, and produce a 50 per cent smaller carbon footprint. There already are a significant number of licensing partnerships that account for a major proportion of the markets in which the new fans could be used. The licensing partners can see the real prospect of 'game-changing' fan technology. Huge amounts of energy can be saved every year, and much more quickly than previously envisaged.[Page Break]

Hybrid flow machines

Processes for which pumps, compressors and turbines are used almost by definition involve highly complex systems for handling a wide range of liquids, gases and multiphase mixtures. Safety is a predominant factor here, given the high pressures combined with high temperatures and chemical compatibility.

The variety of machines is great. The novel hybrid flow machines have similar energy saving potential as the new fans, and worldwide interest has been correspondingly high; the addition of new thermodynamic features means even more savings.[Page Break]

Reduced space

One particularly outstanding feature is the reduced space they occupy - about 10 times less than conventional machines, thanks to the complete integration of the electric motor with the flow machine. This removes the need for engine rooms and thereby drastically reduces total installation costs.

In addition, unique flow features allow new thermodynamic processes of wet compression and expansion, that can cut energy consumption still further.

The market introduction of complicated processes and machines is a more gradual one than is the case with fans used for handling air.

Company practices will be turned on their head, given that the process of understanding and accepting the new energy and mechanical 'laws' of the hybrid flow machines will require a high level of knowledge exchange. The first high-capacity applications are now found in an unexpected quarter: in the 'large' foodstuffs industry, where sustainability is already well established. The potential energy savings for these applications could be as much as around seventy or 80 per cent.[Page Break]

Subsidy effectiveness

For successful projects, the return on investment for the government is exceptional, both directly and indirectly, and easily makes up for the flops that inevitably occur.

Projects would certainly be more effective if there were a less complex system of subsidies, such as a simple taxation measure rather than series of committees and mountains of paperwork. This would make it easier to 'measure' the economic benefits - perhaps it is time to revive the Dutch WIR law (Investment Account Act).

Enter √ www.engineerlive.com/ipe

Femke Schaefer and G Bertels are with Bronswerk Heat Transfer, Nijkerk, The Netherlands. www.bronswerk.com

A mighty monster - Goliath - rules over the Aitik opencast mine in northern Sweden.

To look out over the grey terraces of the immense Aitik opencast mine in the Swedish Arctic is a breathtaking experience. At 3km long, 1.1km wide, and 425m deep, Aitik is one of Europe’s largest copper mines – and it’s still growing.

A recent expansion of the mine included an entirely new way of transporting copper concentrate – a job that is handled by Gällivare Frakt, a logistics firm owned by Nilsson’s father and uncle, Ingemar and Kurt Nilsson. To manage this mammoth task, the company invested in Goliath – a custom-built 540hp Volvo (www.volvotrucks.com) FH16. Fully loaded, Goliath weighs in at 144 tonnes.

Gällivare Frakt transports all the copper concentrate mined in Aitik, which means every day Goliath carries 500 tonnes between the dressing plant and the terminal. From that raw material, about 46,000 tonnes of copper are produced per year.

In addition, Goliath transports about 25 tonnes of silver and 1.3 tonnes of gold annually. With copper currently costing around SEK 58,000 per tonne, this means Goliath transports copper worth about SEK 2.7 billion a year.

Goliath’s daily route is an 8km stretch between the dressing plant and the terminal where the copper concentrate is unloaded. The empty vehicle is weighed then drives into the long, narrow corridor where the copper concentrate is loaded. The hatches on the wagons are opened and the copper concentrate pours into the truck from above.

To unload, the truck is driven into the depot, folds down the support legs, and tips out the load, firstly from the trailer and then the truck. Powerful vibrators then shake out every last bit of the copper concentrate. [Page
 
The new truck, combined with the new loading and tipping system, has helped mine-owner Boliden achieve significant increases in production. Last year, 31.5m tonnes of ore were produced.

AUMA is extending its portfolio of modular electric actuators to include an SQ .2 part-turn range for butterfly and ball valve automation. Scheduled for launch in 2013, the actuators will replace the company’s established SG.1 range manufactured since 1998.
 
A new actuator size included in the SQ.2 series more than doubles the torque range previously offered by the SG.1: this represents a significant expansion now covering 50Nm to 2,400Nm.
 
Other developments include the introduction of an SQR version for modulating duty which replaces the SGR. The SQR provides improved control characteristics with enhanced positioning accuracy and an increased number of permissible starts per hour.
 
Commissioning and operation of SQ actuators are identical to the SA .2 multi-turn type range, introduced by AUMA in 2010. This includes the same control concept: both ranges are without integral controls and are available with simple AM or micro-controller controlled AC. As a result, controls are interchangeable and, at plants where both product series are installed, on-site device management is simplified.
 
AUMA’s newly introduced two-component powder coating has been incorporated into the SQ.2 design ensuring improved corrosion protection. The enclosure protection of the devices meets  
IP 68 - basic standard.
 
Enter √ at www.engineerlive.com/ipe
 
AUMA Riester GmbH & Co. KG  is based in Muellheim, Germany. www.auma.com

A quartzite quarry in Virginia wanted to increase its production and had also been experiencing problems with hole deviation. It replaced its drilling equipment with a Tamrock Pantera rig equipped with Sandvik’s new Sandvik60 drill steel. Productivity has gone up by more than 50 per cent, they’re able to use the same rig at two other quarries – and their holes are straighter. By Steve Minett.

Salem Stone Corporation was started in 1983 when Leonard D. Hill bought the Sylvatus Quarry, near Hillsville, Virginia. Sylvatus is a quartzite quarry and the company now also owns six other quarries in Virginia and West Virginia. Three of them produce limestone products, one ‘accostone’ (which is a limestone variant) and two are sandstone quarries. Salem Stone employs 150 people, 22 of them at Sylvatus. 75 per cent of the stone produced from Sylvatus is used for road surfacing by the states of Virginia and West Virginia. This consists of fractions ranging in size between 3/57 to 2 inches. Other products include three classes of ‘rip-rap’, ‘erosion stone’, for road verges and stone for walling.

Difficult drilling

Roger Ramey, Superintendent based at the Sylvatus Quarry, explains that, “we do all our own drilling and blasting. The drilling conditions at Sylvatus are really quite difficult. The rock is very hard and abrasive and the geology is seamy with vertical fault lines. Hole deviation is a major risk in these conditions. It can result in ‘blow outs’ during blasting, especially if the deviation occurs towards the bottom of the bench. If hole deviation was really significant, we would have to re-drill holes.”

New drilling equipment

This risk, together with a desire to increase production, motivated a major upgrading of the quarry’s drilling equipment. “Eight months ago we had two rigs operating here using T45 drill steel. We decided to replace these and as part of the selection process for the new equipment, we carried out trials of rigs from three different manufacturers here at the quarry. Our drill rig operator, Berlin Cook, had a big say in the final selection. The one he liked best was a Tamrock Pantera rig. We tried out a Pantera 900 using T51 steel, but this really wasn’t big enough for our requirements. So, we finally settled on a Pantera 1100 using the new Sandvik60 drill steel.”

Increased productivity

One of the major benefits from acquiring the new rig has been a very significant increase in productivity: “I’d say it’s increased more than 50 per cent. Firstly, we now using one rig at Sylvatus, where previously we had two rigs. This has been an obvious saving in terms of machine maintenance and having only one driller. Secondly, we’re now also using the Pantera at two other quarries. Previously, the drilling at these quarries had been sub-contacted. So, again, this has been another obvious saving.”

In terms of service life for the drill steel, Roger reports that, “the life of the T45s varied a lot, but I’d say that the average was 8,000 feet. The Sandvik60s, however, are lasting around 14,000 feet. In addition, we’ve got a very good service from the local Sandvik Tamrock distributor on replacement steel.”

The average drilling rate of the Pantera over a week is 3,000 feet. Though it recently achieved a record week drilling 6,000 feet in one of the company’s limestone quarries. And, with the new rig, each foot drilled is more productive, as Roger explains; “Since switching to the larger drill steel, we’ve also increased the size of hole we use from 3.5 to 4 inches. The larger holes mean that we can spread out the pattern of holes we drill for each round.”

Straighter holes

In addition to raising productivity, the Pantera-Sandvik60 combination has also addressed the other major issue which motivated the company to change its drilling equipment; namely hole deviation. According to Roger Ramey, “the hole deviation problems which we were experiencing with the T45 steel have improved by about a third since we switch to Sandvik60. I believe that the female coupling arrangement in the Sandvik60 steels has contributed a lot to this improvement in hole straightness.

More holes a day

Berlin Cook, the rig operator, reports that, “on the old rigs I was able to drill an average of 10 holes a day, whereas with the Pantera and the Sandvik60 steel, I’m averaging 16 a day.” Another feature of the new equipment which Brian likes a lot is the ease and speed of the automated decoupling system; “I’d say that the decoupling process is 50 per cent  faster on the Pantera compared to the previous rigs.”

Fig. 1. Salem Stone recently acquired a new Tamrock Pantera 1100 drill rig.

Fig. 2. Berlin Cook, the rig operator, reports that, “on the old rigs I was able to drill an average of 10 holes a day, whereas with the Pantera and the Sandvik60 steel, I’m averaging 16 a day.”

Fig. 3. The Sylvatus Quarry, near Hillsville, Virginia.

Fig. 4. According to Roger Ramey, Superintendent based at the Sylvatus Quarry, “the hole deviation problems which we were experiencing with the T45 steel have improved by about a third since we switch to Sandvik60.”
 

A specialist, drilling contractor in New England in the US has recently switched to Sandvik’s new, larger Sandvik60 drill steel. This has performed very well with regard to their major drilling criteria – hole straightness. It’s also proved exceptionally easy to decouple and is making their rigs more flexible and competitive as to the hole sizes they can drill.

Gary Davidson started Yankee Drilling in 1984 in partnership with his wife Paula. The company specializes in drilling. “We work in three states in New England; New Hampshire, Massachusetts and Vermont. Almost none of the quarries in this area do their own drilling. Generally, they’ll make a contract with a blasting company, who will then put out a tender for the drilling operations as a sub-contract. The blasting companies are often explosive manufacturers. There are three major companies of this type operating in our area,” says Gary.

Yankee Drilling has 14 employees and 11 drill rigs, of which five were manufactured by Tamrock: “We’ve got three CHA 1100s, one CHA 660 and a Tamrock Ranger 700. I always buy used rigs with the expectation that they’ll run well for ten years. The key, of course, is good maintenance. We do this ourselves but with a lot of help and support from Capitol (Capitol Construction Equipment & Supply Inc. of Bow, New Hampshire, where Gary is a well-established customer) – they supply the parts we need and deal with any problems we can’t handle. We do our major maintenance in January and February when the quarries stop crushing for the winter. December and March are also generally slow months for us.”

Gary’s attention was first drawn to Sandvik’s new, 60 mm drill steel, Sandvik60, when he read about it in a trade journal. “I generally believe that the bigger the steel the better, but at the time we were working in a quarry with particularly hard rock, so I was particularly interested in trying a heavier steel.”

In fact, the rock was so hard that Yankee drilling had to lower the percussive pressure which it normally used. “We had been customarily running the CHA 1100s rigs equipped with T51 steel at 150 bar. When drilling a five-inch hole, this gives us a production of around 100 feet an hour. In this rock, however, which was both hard and seamy, we were getting pitting of the steel, unacceptably high hole wander and actual steel failures.” Tom Donovan of Capitol Construction explains that, “when we measured the temperature of the steel couplings it was registering over 350º F – we consider any temperature above 200º F as too high.”

As a result Yankee drilling had to lower its percussive pressure to 115 bar, which took care of the temperature problem but cut the production rate to only 60 feet an hour, and since Yankee Drilling’s contracts are calculated on a per-foot-drilled basis, this was a serious problem for Gary.

“Given this situation, I was very willing to try the new steel. We switched over to the Sandvik60s. Our CHA 1100 rig had to be adapted, but together with Capitol, we managed this very easily. With the Sandvik60s mounted, we returned to drilling at 150 bar. Our production went back to 100 feet per hour but this time without the problems.” Tom Donovan confirms that, “the temperature of the new steel’s couplings averaged under 200º F. This lower temperature is due almost entirely to the greater straightness of holes drilled with the Sandvik60 steel.” This demonstration left Gary convinced that the Sandvik60 was the steel he’s been looking for. “Given that we’re paid by the foot, the performance of the drill steel is crucial for us. In many ways, I believe that these days it’s the weak link in the equipment chain.”

When asked what criteria he uses to select drill steel, Gary replies, “first and foremost, hole straightness – hole deviation can cause enormous problems both for us and for the quarries: we get a drilling specification from the blasting company. If any of the holes we drill deviates more than a foot in terms of straightness, we have to drill it at our own expense. Then again, hole deviation can cause blasting problems: it can result in ‘fly rock’ – stray pieces of rock from the blast. If these, for example, hit some body’s car, we might end up getting sued. Another problem with crooked holes is getting the steel stuck in them. If we can get it out, the round may have to be blasted anyway. This is also dangerous, and, from the quarries’ point of view, the steel debris has to be got out of the rock before it’s processed otherwise it’ll damage the crushers.”

Gary’s second criteria for drill steel performance is minimizing downtime from production: “Obviously, from our point of view, the faster we can drill, the better. But, of course, there are trade-offs; one is hole straightness and all the problems associated with that which we’ve just discussed. The other is the relationship between the cost of the steel and its service life. Service life issues come in two forms; one is simple durability. It’s maybe too early for us to say how the Sandvik60 is going to perform on this, since we haven’t really been using it long enough, but the signs are looking good – I generally expect to get 20,000 feet out of a single T51 steel and 10,000 feet out of a T51 shank. I’ve now got a Sandvik60 shank that’s already gone beyond 10,000 feet and still looks very good.”

The other service life problem is random steel failures. “This is a special problem for us because we’re not operating on our own sites and we operate over large areas. If we have an unexpectedly large number of steel failures at a particular site, that can mean transporting replacement steel over long distances which is expensive in itself, but also means prolonging our downtime from production. It’s hard to give figures on this type of problem, but it’s my general impression that Sandvik60 is going to help us minimize such costly failures.”

Easier decoupling

Another feature of Sandvik60 which Gary is particularly enthusiastic about is its decoupling: “It’s the easiest steel to uncouple that we’ve ever worked with. Previously we were experiencing a major decoupling problem about once a week, meaning that the decoupling could take up to an hour. I believe that the easier decoupling is related to the cooler running of the Sandvik60. For example, we were getting pitting on the threads of the T51 steel, which made decoupling difficult.”

Competitive increase in hole range

Switching to the new larger steel from Sandvik has also made Yankee Drilling more flexibly competitive. Gary explains that, “in order to increase production there’s a general trend for quarries to want to drill the largest holes they can get away with from the blasting security point of view. The average hole size is still around 3.5 inches, but more and more sites want five-inch holes. Conventionally, holes this big will often be drilled by down-the-hole rigs, which have tended to produce straighter holes, but, on the other hand, are slower and consume more energy. Now that we’re using Sandvik60, we can compete on drilling five-inch holes. This solution has the added advantage for everybody that we can also drill smaller holes, e.g. 3.5 development holes, on the same site with the same rig – we just switch back to the lighter drill steel.” (3 5/8 inch is the smallest hole that can be drilled using Sandvik60 steel.)

Robert Howard describes the negative impact of eroded and deformed burner nozzles and core air tubes.

Coal-fired power plants now have the answer for burner system components failing due to heat deformation or coal particle erosion. Corner fired burner nozzles and core air protection tubes for wall fired burners made from Ceraforte experience extended life times of up to 6 times in operation and are compatible with all burner systems. Ceraforte is a drop in replacement for steel components that fail in operation due to heat deformation and wear.

Since the early 1980s, Elkem Silicon Materials has developed the Ceraforte family of materials through extensive testing, both in their laboratories and in industrial applications. Focusing on properties such as strength, wear and chemical resistance and high temperatures operations up to 1500°C, Ceraforte is designed to be a 'drop in' replacement for steel in burner systems.

All PFC fired units suffer wear, heat damage and slag in their burner systems due to the quality of the coal, choice of wear parts and the operating regime of the plant. Switching from stainless and mild steels to Ceraforte for burner system wear parts will significantly help maintain the original PFC distributions and the design efficiencies of the boiler thus minimising coal usage and downtimes.

Ceraforte maintains it shape throughout its entire lifetime. It is resistant to coal particle erosion due to the Silicon Carbide aggregates and is virtually impervious to thermal shock and heat damage.[Page Break]

Burner Nozzles and Core Air Tubes

Corner fired boilers create a thoroughly mixed fire ball fed tangentially from the corners of the boiler through PFC burner nozzles. This fireball must be kept in a turbulent and free mixing state to ensure optimum combustion. Through the tilting mechanism on the burner nozzle, the fireball is moved up and down inside the boiler furnace cavity to control the temperature of the steam leaving the boiler.

As the original stainless steel nozzles wear out and deform during their 18 to 24 months life, the original PFC distribution and the ability to control the shape and location of the fireball is lost. This immediately and negatively impacts the boiler efficiency.

Replacing stainless steel nozzles with Ceraforte will ensure that the boiler will not operate with efficiency losses due to nozzle deterioration. Further benefits are gained due to the long operating life of Ceraforte in relation to Stainless Steel, effectively 3-4 times longer under the same operating conditions. This means that the burner nozzles only have to be replaced once in every six to eight years, instead of every two years.

With front and opposed wall fired boilers, PFC and primary air is fed into the boiler furnace through circular PFC burners. The point at which PFC and primary air come into contact with the steel components of the burner is the point of change in direction of flow and the point at which most erosion takes place. This erosion is generally severe and causes a considerable amount of down time and repair work.

The replacement of the current steels with a Ceraforte tube over the core air pipe will greatly extend the life of these components. When wear takes place, the tube is rotated to move a new Ceraforte surface into the path of the PFC stream resulting in a lifetime extension of 4-6 times or current solutions.[Page Break]

Ash deposits adhering on the furnace walls in and around the burner zone can cause pressure part wastage, leading ultimately to tube failure and un-anticipated shutdowns. The non-wetting qualities and characteristics of Ceraforte minimises slag in and around the burner zone allowing for a clear and uniform flow path for the pulverised fuel to exit the burner nozzle.

The silicon carbide based material is formulated to be resistant to thermal shock and heat damage and to have high abrasion resistance. Unique among all high temperature materials tested, Elkem Ceraforte actually increases in strength up to 1500°C and can be cast in any shape required. Minimum wall thicknesses begin at 15mm for core air tubes and 25mm for burner nozzles. Trowellable versions can be put directly on the inside surfaces of the burner system and other hard to get areas that are susceptible to slagging. Expected life times are 2-3 times stainless steel in the same operating conditions.

Enter √ www.engineerlive.com/ipe

Robert Howard is with Elkem Silicon Materials, Kristiansand, Norway. www.elkem.com/silicon-materials

Developments in mine communications tend to be based on widespread computer communications in digital form and employ Wi-Fi

Mine communications have come a long way since the only ways of finding out what was going on in a mine were a hard-wire phone, shouting or runners.

Now, rather than wondering, mine management demand virtually instant answers to such questions as ‘Who?’,  ‘Where?’, ‘When?’, ‘What?’ and ‘How much?’. Such information, as accurate as possible, can be sourced and transmitted by modern communications systems as a great aide to mining efficiency and safety, especially in emergency situations.

Efficient and reliable radio systems have been available to increase opencast mine efficiency for many years, but underground mine communications have, until relatively recently, been hampered by obstructions to ‘line of sight’, of which, there are of course many. Various approaches have now been adopted to facilitate communications with little interference from the surroundings.

The wider functions made possible by these technologies are numerous, including tracking of personnel, collision prevention devices, complex data collection and transmission direct to computers, remote-control and monitoring of mining equipment operations including complete automation, and, of course, traditional but more reliable voice communications. Even centralised blast control can be considered a communications function.

‘Leaky feeder’ systems

Just some examples of these systems are mentioned here. ‘Leaky feeder’ systems using local radio transmission to a cable system around the mine are well established but there are now improvements. Telegrid claims that its WZRDnet mesh network provides voice and text communications in mines without the cost of a ‘leaky’ coaxial cable system.

The most sophisticated recent developments tend to be based on now widespread computer communications in digital form and employ a facility for Wi-Fi communications. Mine Radio Systems (MRS) offers an advanced information communications technology (ICT) suite incorporating a range of technologies including fibre-optic networks, radiating cable networks, Ethernet, Wi-Fi networks, mesh networks and a WSN (wireless sensor network). These networks can be used to include an RFID and tagging system, plant fleet management, data transmission, environmental monitoring, video monitoring, VHF & UHF radio communications, Wi-Fi ‘hot spot’ and trapped mine location.

Personal tracking is much more of a safety precaution rather than a ‘Big Brother’ operation. Past mine disasters have shown that more lives might have been saved if rescuers could know where the victims were situated. Mine Site Technologies (http://minesite.net) ImPact overall digital technology meets requirements for real-time data transfer and clear, reliable communications. Within this suite the ImPact tracking system is a Wi-Fi-based system for underground applications. It also provides two-way communication via its VoIP MinePhone, can carry video transmission, and enables laptops and PC tablets to be used underground.

Raising alerts on maintenance

Instrumentation specialist Trolex is employing advanced communication techniques in the monitoring of mine equipment for care issues to raise alerts on maintenance and performance issues. The company is developing cost models to demonstrate savings by improving productivity in the operation of electrical as well as mechanical equipment.

For example, Trolex Commander products collect data from motor starter systems and gears to raise alerts of any recurring ‘trip out’ issues as well as indication of normal operation. The aim is to use real-time data to operate machines just under the trip-out ‘red line’ to reach top productivity without incurring time-wasting trip-out rectification and equipment damage

Video 1: Telegrid's WZRDnet mesh network is said to provide voice and text communications in mines without the cost of a ‘leaky’ coaxial cable system

Video 2: Mine Radio Systems offers an advanced information communications technology (ICT) suite incorporating a range of technologies including fibre-optic networks, radiating cable networks, Ethernet, Wi-Fi networks, mesh networks and a WSN (wireless sensor network)

Video 3: On Show: Mine Site Technologies

Video 4:  Interview with Denis Kent, Business Development Manager at Mine Site Technologies Pty Limited, on reducing collisions in mines

Since the phasing out of canaries in the UK some 30 years ago portable and fixed gas monitoring instruments have taken over. Maurice Jones reports

The miner’s safety lamp and caged canary are emblematic of traditional mining, particularly in coal.

While both these ancient methods are associated with preventing the accidental breathing of ‘nasty’ gases, their purposes are quite different. The flame lamp was, and is, used by a trained individual to test for the presence of methane (fire damp) in explosive or near explosive mixtures.

Extinguishing of the flame can also warn of insufficient oxygen. Canaries were used, at least by rescue teams, chiefly to warn of the invisible, odourless, headache-inducing and ultimately fatal gas carbon monoxide such as generated by combustion in insufficient oxygen. The reliance is that the canary would succumb to the toxic gas before human metabolism, but research later showed that this was not always the case in certain concentrations and exposure times.

In theory, the use of ‘electronic canaries’, as they were first called, and other gas monitoring devices takes out all the guesswork, providing an accurate reading of the gas in the atmosphere. In the context of mining the gases that may be required to be monitored can include methane, carbon monoxide and oxygen (deficiency), plus hydrogen sulphide (poisonous stink damp – sometimes produced from iron pyrites corrosion). There may be also a need to monitor for nitrogen oxides as well as carbon monoxide from blasting fumes and unprotected internal combustion engines.

The electronic devices give direct digital readouts of the gas concentration being monitored and can be set to give audible or visual alarms when a hazardous concentration is being approached or a lower explosive limit (LEL) for inflammable gas mixtures is reached.

Trolex says that a major development area is improved communications, including Wi-Fi, to transmit readings and alarms to a central location for rapid action or data processing. Another is the wider use of multiple gas instruments to give a broad picture of potential hazards rather than only one or two.

Trolex’s Sentro 8 is a flexible multi-gas monitor that also checks on temperature, air flow, humidity, pressure, etc. One application is on major pieces of equipment such as tunnel boring machines that are being used increasingly in mining. The Sentry is a transportable development of the ‘fixed’ Sentro 8 as used in refuge chambers made in the US and China. The Sentry is MSHA and ATEX approved. One of Trolex partners is the refuge chamber manufacturer Strata Worldwide of the US.

Video:  Miners took caged canaries into coalmines in order to provide warning of the presence of toxic gases, including carbon monoxide and methane. Canaries would visibly show distress and sway on their perches in the presence low concentrations of carbon monoxide before toppling over

Laser technology has revolutionised surveying in mines. Maurice Jones reports

The advent of reliable lasers has revolutionised surveying practice both in terms of distance measurement and direction. More recently integration with sophisticated, high capacity control software has enabled a large amount of accurate data to be handled in short periods.

These developments allow many more ‘sightings’ to be taken automatically, resulting in complete scans of a plane or object. In underground mining and tunnelling this practice is now well established to check on the correct excavation profile or installation of lining. In mining such accuracy may not be so vital but a complete high-definition scan can also provide a complete three-dimensional picture of an excavation in much less time than would be taken by conventional surveying techniques.

Surveying safety is also improved by this technology since sightings are ‘remote’, enabling a picture to be formed of unsafe areas such as stopes and abandoned drives without exposing the survey team. An additional precautionary method is to mount the scanner on a remote-control vehicle to enter such hazardous areas.

Mine scanning

Six-West of Belfast, Northern Ireland, undertook a recent example of mine scanning.  The specialist survey firm was asked by exploration company and licence holder Dalradian Resources of Canada to carry out a complete topographical survey of the Curraghinalt gold mine in the province.  Not only did the work provide such an extensive 3D picture but also Dalradian shareholders and potential investors could carry out a virtual ‘walk through’ of the mine from a desktop.

Six-West normal employs a Trimble Faro (http://europe.faro.com/en-gb/home?ext_cid=ef.aw.ge.br.uk.hp.ap) scanner or a Leica  C10 (recently superseded by the Scan Station P20) to measure a 360-degree array at up to one million points per second. The latter was chosen for this task due to wet conditions.

The C10 was set up at intervals of about 50m through all the mine drives, giving 20 set-ups related to previous survey control stations established by Six-West using a Trimble S6 total station and referenced to the Irish Grid and Ordnance Survey Datum. Each full scan took 10 minutes.

Six-West used Leica Geosystems HDS Cyclone software to handle the site data to deliver final output in AutoCAD dxf, ASCII xyz and ‘flythrough’ video formats. As well as the x, y, z data scanners can also measure the intensity of reflected laser light so that lighter objects provide a better ‘return’. Thus the data can also pick up painted references on sidewalls to survey marks and geological features.

Video: Going underground: A demonstration of Leica Geosystems’ C10 Scan Station

Mine planning engineers can create mid-bench based designs, and generate phases and reserve reports

Maptek, the software provider to the mining industry, has released Vulcan 8.2 to a global license base of more than 6,000 users.

The new tools, updates and features in Vulcan 8.2 provide the increased speed, efficiency and usability that modern mining demands. An improved software experience complemented by a walk-through document, release notes and tutorials has been rolled out.

A customer request for generating strategic pit and dump designs prompted development of the new Rapid Pit Design tool, which has been released in Vulcan 8.2.

Mine planning engineers can quickly create mid-bench based designs, and generate phases and reserve reports. With this tool users can evaluate multiple designs in the same amount of time they would traditionally create a single design.

"The new tool helps engineers to quickly create and analyse different pit designs, allowing them to look at many more alternative designs, prior to producing a final design," said Steve Uecker, Vulcan Client Experience Manager.

Vulcan 8.2 includes a new Support Analysis tool for resource validation and forecasting with practical applications in all stages of mining. Users can quickly generate grade tonnage curves at varying scales or material classifications, verify the choice of block size and validate resource block models.

Vulcan 8.2 is equipped with a 256 indexed colour palette with 24 bit colour depth, expanding the selection to more than 16 million colours for CAD objects.

Upgrades to the CSV import option allow users to bring in .CSV files without first creating a template. Updates to the Excel interface in Chronos improve the scheduling workflow.

Following the initial release of Vulcan 64-bit in April, Vulcan 8.2 is available in 32- and 64-bit. Access to the entire 64-bit memory space greatly benefits users working with larger datasets.

Maptek has been delivering more frequent releases to get new functionality into users hands quickly, and encourages users to take advantage of the new tools by upgrading their version with each release.

"Rigorous internal quality assurance and our customer beta testing program helps to ensure that Vulcan 8.2 combines robust software with a great user experience," says Uecker. "We increased test assets by 53 percent for this release and feedback from our beta testers has been very positive overall."

Video: Maptek Founder and Chairman Dr Bob Johnson looks back over 30 years of innovation and success at Maptek

The improved reliability of conveyors allows their use over more uneven terrain including horizontal and vertical curves. Maurice Jones reports

The choice of ore and waste transport method is one that requires careful calculation of all the economic implications based on factors such as realistic reliability expectations, flexibility for changing circumstances, manpower requirements, energy consumption, maintenance requirements and, not least, capacity. In many cases belt conveyors are an ideal option, but it is a big decision affecting the economics of the whole mining operation.

As the average life of expectancy of mines reduces the main consideration turns to flexibility in bulk transport, but, as with shaft winding, if it can be shown that a trunk transport route is unlikely to change frequently, then a belt conveyor can easily be the best option. Belt conveyors are of particular value for low density, lower value minerals, such as coal, and where the available space is limited, such as in underground sections.

Even on the surface belt conveyors are a valued option such as where the mine layout allows the establishment of semi-permanent transport on one alignment, or where a transport route can serve several mines, pits or a central processing plant or dispatch facility. Where planning considerations allow, belt conveyors can be used over long distances from mines to, for example, a port.

Modern technology, and improved reliability, of conveyors allows their use over more uneven terrain including horizontal and well as vertical curves, and minimises necessary supervision. The need for reliability of conveyors in main transport locations cannot be over emphasised since a fault can halt all mine production, whereas one truck breakdown, for example, will result in a relatively small production shortfall.

‘Overland’ conveyors

RBL-REI of France has long specialised in long-distance conveyors including underground and surface installation, especially ‘overland’. Its range of available technologies include Curvoduc installations to tackle multiple horizontal and vertical curves, downhill conveyors that regenerate energy to significantly reduce overall power consumption and covered ‘tube’ conveyors to prevent dust emission and deterioration of fragile minerals.

A recent overland installation in a New Caledonia nickel mine included a series of Curvoduc conveyors with a capacity of 770t/h using a belt speed of 3.5m/s.

The world's biggest tractor – the Tractomas  - is now in operation at an Australian coal mine

For use in a coal mine in Australia, the French heavy-load and special vehicle manufacturer, Nicolas, has produced a new type of world's biggest tractor, the Tractomas.

The 1,000hp vehicle has twice the pulling strength than previous tractors on the market and has been purchased by the LCR company (http://www.lcrgroup.com.au) for moving convoys of lignite side tipper trailers at its mining facilities in the Australian state of Queensland.

The truck dimensions are impressive - more than 10 metres long, 3.5 metres wide and 4.6 metres high. Except for the driver's cab that comes from truck mass production, everything else is specially constructed.

The new Tractomas was delivered to the Australian company LCR that undertakes large-scale projects such as transportation and lifting technology especially in the mining industry. Here, the super truck pulls long convoys of oversized side tipper trailers with an overall towing weight of 535 tons.

Transport distances range between 10 and 40 kilometres and gradients of up to 5 per cent have to be mastered. The Tractomas scores here with 10 km/h when fully loaded, in this case with side tipper trailers that can each carry up to 87 tons of coal.

On straight routes without any gradients, a speed of 50 km/h (loaded) and up to 65 km/h (unloaded) can be achieved. This is made possible through the 1,000 hp engine with 27-litre capacity.

No loss of speed

However, this can be increased still further. In connection with the Nicolas PowerBooster auxiliary drive system, more performance can be achieved. The PowerBooster feature in the Tractomas prevents loss of speed when negotiating inclines.

As soon as the power output of the tractor on gradients is found to be inadequate, the PowerBooster cuts in automatically and provides sufficient driving force. An additional advantage is the improved cooling performance through the PowerBooster. Thus, transports can be carried out without any problems even under extreme climatic conditions, for example at 50°C in the desert.

These features make the Nicolas Tractomas the fastest and strongest heavy-load tractor currently available on the market and, as a result, ensure more economic efficiency in logistical operations in the mines. In July, the first vehicle was officially handed over to the LCR company in Australia. Orders for additional vehicles have been placed with Nicolas.

Video: For use in a coal mine in Australia, the French heavy-load and special vehicle manufacturer, NicolasI, has produced a new type of world's biggest tractor, the Tractomas. The 1,000 hp vehicle has twice the pulling strength than previous tractors on the market and has been purchased by the LCR company for moving convoys of lignite side tipper trailers at its mining facilities in the Australian state of Queensland

Mining Machinery Developments (MMD) has undertaken a multi-million pound factory expansion featuring new cranes from Street Crane Company.

The cranes will speed the manufacture and assembly of MMD’s heavy duty mineral sizing equipment.

A mix of overhead travelling and jib cranes provides a flexible system for efficient and reliable lifting, handling and production flow that can be easily adapted to meet future expansion.

Two new bays have been added to MMD’s factory for the manufacture of heavy fabrications. Three 20 tonne overhead cranes in each bay run on full-length freestanding 60 metre gantries. The cranes will be used for offloading vehicles and advancing product through the various stages of production. Having adequate cranage in the production area ensures optimum levels of productivity as the highly skilled workforce do not have to wait for cranes to become available.

The cranes are double girder box beam design and feature infra-red anti-collision systems so they can safely operate on the same track.  For heavier lifts of up to 40 tonnes, they may be used in tandem and weight distributed by a spreader beam.

The new bays are also equipped with 10 one-tonne jib cranes, with seven units in one bay and three in the adjoining bay. Each one supports a workstation manned by two welders or platers. The slewing jib cranes are attached to the gantry legs with fittings that can be dismantled, enabling the jibs to be readily re-located as production needs change.

The 20 tonne overhead cranes feature hoists from Street’s ZX series. An advanced specification hoist designed for reliability and ease of maintenance, the ZX offers true vertical lift and placement. The 50 tonne cranes feature custom built hoists from Street’s VX series. These heavy duty hoists also offer vertical lift to safeguard product from lateral movement and assure greater safety. The one tonne jib cranes all use chain hoists from the company’s LX series.

Video:UK Chancellor of the Exchequer, George Osborne, visits Street Crane meeting Directors and workers

Wear, corrosion and abrasion resistant materials are vital to the mining industry. Rubber products are key to the protection process

Rubber products are used to protect valuable mining assets, including the lining of screen under-pans; small and large bore piping; pump sumps; chutes; cyclone clusters; flotation cells, CCD thickeners; and ball mill backing rubber, to name a few, in the gold, nickel, copper, alumina, iron ore and uranium and mineral processing industries.

The distinctive red colour of Linatex-brand rubber - from Weir Minerals Malaysia - came into existence in 1923 when Bernard Wilkinson invented a rubber (known today as Linatex Premium rubber) to support the need for improved wear resistant materials used in the bourgeoning tin mining industry of Malaya (now Malaysia)

As a British planter on a rubber estate in Malaya, Wilkinson experimented with fresh rubber latex compounds. Wilkinsons 'liquid phase' process enabled him to maximise the retention of the physical properties of natural rubber in a commercially produced sheet.

The superior wear resistant qualities led it to be used predominantly in the mining industry to rubber-line piping and machinery used in highly abrasive minerals processing applications, especially where plant down-time can cost the operator significant loss of profits.

Dr Norman Keane,  Business Development & Innovation Director for Weir Minerals Malaysia, says: "It is not uncommon for manufacturers of inferior rubber to illegitimately pass them off as Linatex Premium rubber by colouring their rubber with something approximating the trademark Linatex red colour. We are often called to a site where the customer tells us they specified Linatex Premium rubber only to find that - while it may have been a red rubber ­ it didn't perform to the same standard as Linatex Premium rubber."

Dr Keane says: "A cheap rubber can appear attractive even though the higher end product may result in three times the wear life."

In a case study at a Western Australian mine site (see diagram), by following the chain of events that led to the end user installing a pipeline on site that was lined with inferior rubber, the case study highlights the true 'cost versus performance' scenario.

Using a high end product, such as Linatex Premium rubber, to line a pipeline, one needs to take into account the costs of adhesives, labour, surface treatment, transport and the rubber material. The fabricator then adds the costs of the completed and treated steel piping.

The pipeline is then transported to site and installed; and the overall cost differential between the two options may then be as little as 7-10 per cent as shown in the case study. With the expected life of a product like Linatex Premium rubber being potentially up to three times that of a cheap imitation red rubber, some customers may be tempted to accept a product that often can provide two to three times less life for an upfront saving of only around 10 per cent as shown in the case study.

"This scenario is a fairly common occurrence, especially in the construction of new mines," says Dr Keane.

Dr Keane says mine operators today face big challenges.

"The industry is focused on future growth through expanding production and increasing yield, without losing sight of operational efficiencies and cost optimisation. It is also faced with the increased challenges of maintaining social responsibility, skills shortages, effectively executing capital projects and meeting revenue expectations. In addition, operators also face the challenge of increased capital project risk and general global uncertainty resulting in volatility of commodity prices."

The Weir Minerals Malaysia manufacturing plant is certified to ISO 9001:2008 guaranteeing that the process is operated according to certified operating standards.
 

The Kopex-Ex range of electrical conduit systems for use within hazardous areas are designed to protect and connect critical power and data cabling in many different industries, including oil and gas, mining, pharmaceutical and food production. These industries are all bound by global or national legislation including ATEX, UL, IECeX, GOST and CSA.

The Kopex-Ex range for Exe and Exd applications is just part of a comprehensive range of products for use in hazardous area markets. Conduits and fittings for use in potentially explosive environments include liquid tight and nylon conduit systems, together with a full range of connectors adapters, reducers and enlargers.  In addition, the XP-Flexible Coupling Range features UL Listed Class I Div Explosion Proof products.

All products are engineered to include the critical properties needed to withstand the most demanding of operational environments. 

Key performance characteristics  include the ability to offer  resistance to the ingress from water, damage from oils and chemicals as well as the ability to withstand continuous vibration. Anti-corrosion properties, specific fire performance and EMI screening capabilities are included too.

For more information, visit www.tnb-hazardous.com or www.kopex-ex.com

Methane monitoring specialists Trolex has introduced Sentrum, a device delivering accurate and reliable methane recovery monitoring.

The Sentrum system has already been installed in many mines around the UK, China, Australia and South America including involvement with Alkane Energy and an EU funded methane extraction project. 

Sentrum is the first system of its type that is certified for use underground and the first to be able to differentiate between methane and other non-methane hydrocarbons so accurately. It does this by sampling the gas on a continuous basis and uses infra-red detection coupled with other special processes. It uses an initial gas analysis to ‘train’ the system and subsequent analysis can be used for fine-tuning.

Removing methane gas from underground coalmines is a very necessary safety measure yet a new awareness of the value of waste gases for power generation, or for direct sale to aggregators, has led to a demand for increased accuracy in monitoring the extraction processes for these gases.

In the EU funded methane extraction project based in China and India, a remote data monitoring system is employed providing real time information to the UK for analysis.

Thirty Trolex Sentrum systems are installed at 15 Alkane Energy sites across the UK.

Wayne Straw from Alkane Energy explained why they chose the systems: “Accurate gas analysis and monitoring is vital for safe and successful utilisation.  We are generating electricity from expensive generator sets and providing the best protection is paramount.”

Trolex designs, develops and installs monitoring packages for methane drainage and methane extraction monitoring. Trolex’s methane recovery monitoring systems are precision-engineered to meet the needs of each individual project, and are installed by a dedicated engineering team to ensure full system compatibility and safety integrity for working in hazardous areas.
 
To highlight the necessity of using reliable gas sensing equipment in potentially dangerous environments, Trolex has launched a Sentrum microsite that is dedicated to its methane recovery monitoring systems.

For more information, visit www.methanemonitoring.net