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Crescendo of activity in alternative fuel energy sector

If you’ll pardon the pun, activity is really heating up in the alternative fuel combustion market as a number of projects are commissioned this year. For Saxlund it’s a busy time and we are on schedule to deliver more than 13 alternative fuel handling solutions, supporting a variety of combustion and gasification projects in the UK alone. Most of these are now either waiting to be commissioned or already undergoing production trials.

Galliford Try Infrastructure, for example, appointed us back in 2016 to design and deliver the bulk fuel reception and handling technology for three waste wood gasification facilities in Barry, Boston and Hull, for the renewable energy company Biomass UK. All three projects are at an advanced stage, pending dry or wet commissioning, with project completion expected in the second half of 2017.

Galliford Try Barry Infrastructure Push floors
Galliford Try, Barry, Infrastructure Push floors

Other sites include the Tansterne Advanced Biomass Project in Hull for HRS Energy where the first of two fuel streams is already commissioned; fuel handling solutions for Bouygues Energies & Services at two waste-to-energy gasification plants, one at  Hoddesdon in Hertfordshire and the second in Belfast; a fuel reception and delivery solution for a pioneering green gas generation plant at Marston Gate in Swindon for Go Gree Fuels; three projects with Babcock & Wilcox Vølund A/S, for biomass powerplants at Templeborough in Sheffield, Margam in South Wales and in Teesside; and a fuel handling solution for M+W Group the lead contractor for the Surrey County Council SUEZ operated Eco Park,  at Charlton Lane in Shepperton.

Tansterne Advanced Biomass Project
Tansterne Advanced Biomass Project

Expectations

Customers appointing Saxlund expect several things, but fundamentally they are looking for high availability, low maintenance solutions to ensure the plant achieves the projected output in terms of energy production, and in tandem with this the financial returns that shareholders are anticipating, without whom many of these projects would not be achievable. 

Engineers who have worked with biomass and other alternative fuels will appreciate the challenges and will, no doubt, have experienced some of the issues that these fundamentally difficult fuels can present.

Troubleshooting

Mouldering and stagnated fuel heaps and constant recourse to air lances and the like to remove obstructions and restore flow have plagued many sites over the years, with constant stoppages and downtime. As an engineering design house, we frequently find ourselves troubleshooting systems that aren’t delivering, either where the original design has been defective in some way, or where the finances haven’t allowed a sufficiently robust solution in the first place.

Maintenance, or more particularly planned preventative maintenance, is another area that sometimes doesn’t receive enough upfront consideration. While it might be tempting to push machinery fractionally beyond its operating window, unplanned maintenance shutdowns due to breakdowns are likely to be costlier to rectify with consequences to downstream processes and supply chain deliveries.

Push-Floor-discharge-conveyor
Tansterne Advanced Biomass Project in Hull Push Floor discharge conveyor

Fuel characteristics

Biomass and alternative fuels such as Refuse Derived Fuel (RDF), now on the increase in the UK, and Solid Recovered Fuel (SRF), share similar characteristics. They are typically non-free flowing, wet and liable to compact and will happily form bridges in silos and chutes. So the potential to disrupt downstream processes shouldn’t be underestimated.

Material characteristics can change too, delivery to delivery, and we frequently see over-optimistic expectations when it comes to feedstock quality and consistency.  Even a reasonably consistent input material like waste wood can throw-up surprises. One in ten truckloads for example may be largely or completely composed of fine dust. Others may be black and compacted having been stored too long.

RDF with mixed organic residues can be even more challenging. These factors may be outside your control and will test the capabilities of installed handling systems if the design is defective, resulting in poor or erratic material flow, stagnant product and costly periods of outage.

Future proofing

Over the lifetime of a plant, twenty-five years or more, its quite conceivable that fuel specifications will change too, or that you need to switch to a different fuel, say from biomass to RDF.  Planning for this at the design phase is also essential.

Returning to the fuel storage and handling projects in Barry, Boston and Hull for Galliford Try Infrastructure, future proofing the design specifically for this reason has been a key design focus from the outset.

Each site is similar with twin Saxlund Push Floor storage bunkers discharging waste wood into a conveying and screening system. This incorporates oversize material and ferrous metal removal and weighing systems before feeding fuel to twin gasifiers. At each site one of the Push Floors is designed to accept straightforward modifications to handle RDF, extending the operator’s fuel flexibly if supply pressures occur.   

Each system will provide on-site storage for approximately 600m3 of waste wood and is designed to discharge some 100,000 tonnes of fuel per annum.

Screening-Tower
Galliford Try Infrastructure, Boston, screening tower

Good design

Good design is clearly essential if you want a fuel feed solution that works from day one and is also reliable. The temptation to select cheaper ‘equivalent’ solutions will be attractive if CAPEX expenditure can be reduced, but it makes no sense if the result is higher operational costs to resolve fuel feed issues, with expensive manual interventions and costly fixes.

Design direction to provide sufficient fuel storage, plus reclaim and conveying systems, will also be dictated by site constraints and available space, factors that are sometimes overlooked at the early stages of project development.

Permitted vehicle movements for example including delivery hours and weekend working will also determine storage requirements and truck reception systems, and there may be environmental factors at play, including noise, dust and water run-off to consider.

Whether you are processing fuel onsite or relying on shipments from third parties, fuel cleanliness will also be important with a requirement for oversize and undersize screening and metal removal. Weighing and sampling might also be required to monitor quality and deliver fuel at precise rates to the combustion process. Together with reception systems, storage systems and reclaim conveyors, these are elements that need to work together seamlessly, and for the life of the facility. 

For Saxlund engineers key technologies for handling and storage revolve around activated surfaces and ‘first in, first out’ principles. This limits the opportunity for fuel to degrade and for most materials some form of Sliding-Frame or Push-Floor system is advisable. These make for dynamic rather than static storage and ensure that easily-compacted materials are kept on the move.

In general terms, a system design that favours vertical rather than inclined surfaces, broad rather than narrow channels and positive handling options such as screw-feeders and chain conveyors will minimise problems.

For most projects delivering the energy output required to make the plant viable will always be a major focus, but this shouldn’t ignore the fuel feed and handling aspects of a project. One is very much dependent on the other. Design features to overcome difficult fuel characteristics and to ensure full availability are clearly important.

Early engagement to allow a holistic approach is also beneficial and planning for changing fuel specifications, which may be outside your control, together with appropriate maintenance, must all be factored into the solution you choose. These are some of the reasons why clients select Saxlund International and with more than 60 years’ experience, we can ensure that bulk fuel handling solutions aren’t a weak link in your energy project too.

Why New Cake Handling Systems Reduce Costs by 75%

The 20th European Biosolids & Organic Resources Conference is Europe’s foremost conference for the biosolids and biowaste industries and this year as well as reviewing sludge developments to date, will be exploring future solutions.

Due to my work with Utilities and Contractors in the Water Industry I was asked to demonstrate at the event some of the cost benefits Anglian and United Utilities are seeing from their innovative truck loading silos and sludge reception technology for digestion satellite and hubs, which is contributing to their overall gas generation model.

By MARK NEAL

Innovative water companies are trying to be more efficient and cost effective and reduce their carbon emissions. Some are already changing their focus from water supply / waste treatment to energy generating. They are looking at the potential of sludge in a new way – as a possible source of profit rather than a cost. Why?

Instead of thinking of sludge as a cost centre and something to be disposed of, many water companies are deciding that generating gas from sludge at large water treatment sites (hubs) and transporting sludge from smaller treatment works (satellites) to hubs will be the model of the future. As part of sludge treatment improvement facilities, forward thinking water companies have Anaerobic Digestion and Thermal Hydrolysis infrastructure such as these already in operation:

Davy Hulme being fed by 7 satellites (Wigan, Preston, Hyndburn etc.) by United Utilities Colchester, Cliff Quay and Pyewipe being fed by more satellites (ie Thetford, Bedford, Marston, Dovercourt, Canwick) by Anglian Water’s

With UK population predicted to reach 71 million by 2030, there will inevitably be more sludge to deal with in large cities and towns. By treating this as an opportunity to generate energy rather than a problem, companies are building Anaerobic Digestion Plants and Thermal Hydrolysis infrastructure near large population centres and creating smaller satellite stations to store the sludge.

This pioneering method collects the sludge from the satellites, dewaters it and delivers it to the hubs for processing. Not only is the storage solution more efficient in construction, but in operation and efficiency also.

BENEFITS

  • Energy creation instead of waste sludge disposal
  • No container rental costs
  • No requirement to regularly swap full containers
  • Fewer staff needed at all times, including bank holidays
  • By storing the sludge in new innovative ways, the plants become more flexible and the satellites capture more fuel (sludge). The solutions demonstrated focussed on the storage and discharge of Sludge, these included Truck Loading Silos, Truck Receptions Silos and Process Silos for Advanced Anaerobic Digestion.

To reduce costs further, Anglian and United Utilities chose to dewater the sludge to reduce the cost of transporting water so choosing “trailered cake @ 22%” Dry Solids instead of “tankered wet @ 6% solids.” This choice means they use 1 truck instead of 4, so saving costs of up to 75%.

ADDITONAL BENEFITS

  • Reducing haulage costs by 75%
  • Have more sludge available to process
  • Not hauling sludge borne water between locations
  • Saving fuel
  • Up to 4 fold reduction in CO2

How it works

Each storage unit is discharged by the same technology and features the same benefits. In each case, a Saxlund Sliding Frame mechanism is used to undercut the full section of the contents of the silo to prime a screw trough. Materials are discharged on a “first-in, first out” basis – important in handling materials with a shelf-life. Since the whole section is undercut, the pile section discharge is termed “mass-flow” (like laminar flow in a pipe) from the silo. This gives a homogenous discharge to the next process.

Where there is some dewatering requirement for the dilution of the sludge prior to the next process, the most efficient mix is controlled via the injection of final effluent in the pressure cavity of the Progressive Pump. Since the Progressive Cavity pump auger has already been primed by the action of the Sliding Frame and Saxlund Discharge Screw, a volumetric mix ratio between the Sludge and Final Effluent can be measured by comparison of revolutions between the Dilution and PC Pumps. This can otherwise be more random with the method of filling the inlet hopper of the PC pump with final effluent and expecting the PC Pump Auger to prime the PC Pump.

With 60 years’ experience in delivering BioEnergy projects across Europe, Saxlund holds patents on key technologies to improve feed and combustion efficiency which in turn reduce fuel costs and carbon emissions.

With its UK engineering and project management office based in Southampton, we are currently collaborating with Tier One and Tier Two water companies, consultants, contractors and investors, to deliver truck reception systems as Saxlund’s sliding frame technology, tested in hundreds of successful applications, is the only real solution for discharging sewage sludge silos at this size.

To learn how Saxlund technology could help you, please contact Mark Neal – info@saxlund.co.uk

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Biomass Solutions, WfE and Bulk Materials Handling – RWM 2015 – Stand 4B33

Saxlund International is exhibiting at RWM 2015 on September 15th to 17th in halls 4/5 stand 4B33.

RWM is one of the biggest European events for companies researching & actioning the best solutions for resource efficiency and waste management.

Saxlund is a leading specialist in biomass combustion, Energy-from-Waste, alternative fuel systems for cement works and bulk materials handling solutions. We will be outlining our European-wide capabilities and the latest technologies we have deployed across a range of current and new projects.

These include small to mid-scale biomass fired CHP plants in the UK, Sweden, Estonia and Lithuania, energy from waste solutions in the cement industry, as well as new bulk materials handling solutions such as the new 3 million Euro contract to provide a state-of-the-art biomass multi-fuel handling system for a 40 MW green energy project in Margam, Port Talbot for Babcock & Wilcox Vølund, which is due for commissioning in 2016.

Saxlund’s involvement covers the design, manufacturing, delivery and commissioning of two fully automatic fuel handling systems, providing 100% redundancy, including  fuel reception, conveyor feed systems, mixing and fuel storage.

Due to begin production shortly, Saxlund will also be discussing experiences at the new 3.4MWe waste wood biomass CHP power station based at Twinwoods Business Park in Bedfordshire. Key components of the project include proven Saxlund fuel handling and push floor technology, conveyors, biomass combustion boiler and associated equipment feeding a Siemens turbine.

Managing Director Matt Drew says:

“The Renewable Heat Incentive offers a real window of opportunity in the UK for the development of small-scale, waste wood biomass plants, and we are busy collaborating with a number of new partners who see the value of consistent green base-load energy. There is increased interest across the board from energy producers, large business consumers and district heating groups for onsite CHP biomass power solutions. Appropriate technology, realistic project outcomes and the right investment partners remain essential, but at Saxlund the combination of our project management skills, our Combustion Centre of Competence and 100% success rate, put us in a uniquely strong position.”

With 60 years’ experience in delivering BioEnergy projects across Europe, the company holds patents on key technologies to improve feed and combustion efficiency which in turn reduce fuel costs and carbon emissions.

The Southampton-based company is currently collaborating with consultants, contractors and investors, to deliver biomass combustion solutions for combined heat and power (CHP) plants, district heating, electrical production and process steam for manufacturing. Solutions are capable of converting from 6,000 to 80,000 tonnes of waste wood per annum to produce renewable energy and heat, a fuel source that would otherwise be sent to landfill or exported.

To book your free tickets or find out more about RWM 2015 click here –  RWM 2015

Contact Saxlund  International and book an appointment to discuss waste management solutions at RWM 2015 here – Email: info@saxlund.co.uk