Developments in the use of biomass as a replacement for power generation coal in Europe has quickened pace as evidenced by growing exports from the USA, Canada, and West Africa, writes Walter Mitchell.
The essence of biomass is organic plant-based material that contains stored energy. A product of biomass that has grown in favour is wood pellets, which is compressed wood product. When it is extruded, the lignin that is resident in the wood helps bind the wood particles together. The bound wood is dried and compressed, which serves two critical purposes: 1) it increases energy content as a function of volume, and 2) allows the product to handle similarly to a dry bulk material that is suitable for marine vessel handling. The finished product has relatively little carbon, which makes it desirable for carbon abatement in generation firing, and in NOx and SOx stack
THE DEMAND MANDATE
European demand for biomass has been triggered by the EU’s announced ‘Europe 2020’ programme in which climate change and energy initiatives are specified under the title ‘20/20/20’. This aspect of the programme sets the following targets:
- reduce greenhouse gas emissions by at least 20% compared to 1990 levels (or by 30% if the conditions are right);
- increase the share of renewable energy sources in final energy consumption to 20%; and
- increase energy efficiency by 20%.. To meet the first two targets, converting fuels from those with high carbon footprint to those with low carbon footprint becomes necessary. Europe has done considerable work in the solar and wind sectors, and recently has embraced utilizing biomass as an additional measure as part of these strategies.
A number of EU power generation companies have committed to using biomass as either primary fuel or as supplementary fuel to co-burn with coal, and it is in this sector where there has been significant growth in marine deliveries. As example, in the UK, many of the ageing coal plants have been scheduled to be withdrawn from service because of the mandated emissions requirements under the Large Combustion Plant Directive (LCPD) and the Industrial Emissions Directive (IED). Firing with biomass provides the opportunity to keep the plants operating beyond withdrawal dates, avoids massive capital investment to replace, and reduces stack emissions.
WOOD PELLETS AS MARINE CARGO
As a cargo, wood pellets are somewhat similar to grain. Wood pellets stow at 53–57 cubic feet per tonne with a similar angle of repose as grain. As a result, high cubic capacity vessels are not necessary, although some have been chartered for the business. In one case, a modern NYK-operated wood chip carrier has been fixed. In other cases, log carriers and vessels with the box- hold configuration such as found in the Saga Forest Carriers fleet have been fixed. Other vessels transporting trans-Atlantic wood pellets cargoes are in Lauritzen, Norden, Oldendorff, Spliethoff, and FedNav fleets. In the case of Norden, wood pellets now comprise its second largest dry bulk cargo volume transported, next to coal. Moisture content ranges from 5% to 7%, and fortunately does not migrate in the cargo column during the voyage. However, the cargo is hydroscopic requiring covered storage and suspension of loading and hatch closures should rainfall during cargo operations become significant.
The indicated vessel is a single-deck bulk carrier with economies of scale matched to the vessel size restrictions of the port pairs. The largest vessel we’ve seen in the trade is a Supramax. At loading, crews trim the vessel as completely as possible to mitigate oxygen in the cargo hold, using small but effective trimming machinery to complete each hold. Holds are topped off to the underside of the hatch cover in effort to eliminate oxygen in the hold. Most vessels are CO2-fitted, and this is becoming a requirement for vessel fixture.
While most vessels in the fleet and in this size range are geared for self discharge, the discharge piers in most European ports have on-quay cranes and grabs. Even as the pellets are relatively sturdy, care is taken to avoid pellet degradation and creation of fines caused by grab discharge.
RISI forecasts that in order to meet the Europe 2020 targets, the EU will require imports of near 20mt (million tonnes) by the year 2020, however other forecasts indicate a much higher requirement. The main import countries in Europe of industrial- grade wood pellets at present are the UK, the Netherlands, Belgium, and Denmark. Minor importers include Sweden, Italy, and Latvia. Some specific end-user situations are described below.
DRAX Power Station, by far the largest coal-fired generation in the UK, has committed to burning biomass in three of its six generating units, involving investment of close to US$1 billion. In July 2012, DRAX confirmed its plans to transform itself into a predominantly biomass-fuelled power generator. The first unit will have completed conversion in the second quarter of 2013, and the second in 2014. The indicated annual biomass fuel requirement is 7.5mt by the year 2017.
Imports will be handled at three ports: Port of Tyne – 2mt existing capacity; Hull – 1mt under construction; and Immingham – 3mt contracted. In the case of existing capacity, the Port of Tyne has invested over £20 million to handle, store, and transport wood pellets imports.
DRAX receives considerable supply of wood pellets from US Gulf and East Coast ports. DRAX is also an investor in two wood pellet plants in the USA that are planned to come on stream in 2014, with combined capacity of 900,000 tonnes production.
RWE. In 2011, the Tilbury B power station on the River Thames was converted from using coal as primary fuel to 100%
biomass, using wood pellets for the remainder of its lifetime under the LCPD. RWE is reviewing life extension of the station which would allow it to operate as a dedicated biomass power station for an additional 10–12 years beyond its LCPD date of 2013. To meet what are called ‘New Plant Standards’, the power station must be significantly modified, and upon completion would be renamed Tilbury Biomass Power Station.
The new station would consume approximately 2.7mt per annum of wood pellets that would be sourced primarily from the USA South, Canada, and within the EU. Currently,Tilbury is consuming approximately 1.3mt wood pellets.The plant utilizes a just-in-time pellets delivery system whereby the delivering vessel represents the fuel stockpile.There is no virtually no biomass stored onsite; instead, the wood pellets arrive on a vessel and are unloaded and burned during the course of a week. Once the vessel completes discharge and departs, another vessel berths alongside within hours and the plant fuelling process starts again.
In 2005, the Electrabel subsidiary of GDF SUEZ achieved a world first by transforming the Awirs power plant in Flémalle, Belgium from burning all coal as fuel to burning all wood pellets. Wood pellets consumption is noted at 1,200 tonnes per day, equating to approximately 425,000 tonnes per annum. Because of its inland location, Awirs receives product by barge on the Meuse, and by truck.
Another Electrabel plant, Rodenhuize, is also burning 100% wood pellets at a reported rate of 700,000 - 800,000 tonnes per annum. Approximately 45% is imported from the USA South, and approximately 30% from Canada.Agreements have been concluded with Pacific BioEnergy of Vancouver, BC, and with Enviva LP, of Bethesda, USA. Pacific BioEnergy will export 225,000 tonnes per annum over ten years from production in Prince George, BC. Enviva reports an annual supply agreement with Electrabel of 480,000 tonnes over a long-term agreement. Shipments are received at the Port of Ghent. Verdo A/S has contracted to import 750,000 tonnes over 5 years of Ghanaian wood chips (as opposed to pellets) for the company’s biomass activities.These activities are planned to include trading and internal consumption at Verdo’s owned CHP plant in Randers, Denmark. The biomass comes from rubber trees, which no longer produce rubber. Cargoes are loaded at the small but diverse Ghanaian port of Takoradi, and shipment lots to date have been small, in the 10,000–15,000-tonne size.
With the Ghanaian agreement,Verdo secures long-term delivery of high quality biomass with Norden, a compatriot shipowner and operator. Imports are discharged at the Port of Aarhus.
Verdo points out that supply from Ghana instead of nearby Baltic ports avoids the delays and other logistical problems posed by wintertime ice in ports and waterways.
Half of the imported biomass is consumed at the CHP plant at Randers.The other half is resold to other energy companies.
DONG Energy. Since 2004, DONG Energy has used wood pellets as fuel at its CHP plant ‘Avedøreværket’ south of Copenhagen. Wood pellets replace coal, gas and oil in one of the plant’s two boilers. In 2011, Dong burned over 1mt of biomass sourced primarily from the Baltics, Poland, and Russia, and has commenced importing from the USA South.
By 2020, Dong Energy intends that biomass will constitute at least 50% of its Danish heat and power production. In 2012, biomass constituted 21%.
E.On has placed a second wood pellets-fired unit on line at its Ironbridge UK plant. Ironbridge retains the capability to co-fire up to 20% coal.Total wood pellets consumption is expected to be 1.75 million tonnes per annum. Importation would be via an east coast UK port, such as Tyne or Immingham. E.On has entered into a multi-year supply agreement with Enviva LP for marine deliveries from the USA, and DCi has learned that there are a number of agreements in place to supply Ironbridge. As is the case with many of the European consumers, there is also significant supply tonnes from on-Continent sources as well as those within the UK.
Vattenfall of Sweden aims to reduce the use of ’hard coal’ by 40% in the company’s power stations in Denmark, Germany, Poland and the Netherlands before 2020. It had at one time a three year transportation arrangement for the delivery of 600,000 tonnes of wood chips (not pellets) from Liberia in approximate 25,000 tonne lots, although it has sold its interest in that production to its joint venture partner and is believed to be focusing on biomass projects within Europe.
THE SUPPLY MANDATE
To meet this demand, USA wood pellet producers have ramped up production considerably from the 2007 level of 650,000 tonnes. According to RISI, USA exported very close to 2mt in 2012, a 52% increase from 2011, and including exports from Canada, the 2012 volume from North America to Europe is more than 4mt. RISI further forecasts that by 2017, export tonnage will reach 10mt with the USA responsible for 5.6mt and Canada the remaining 4.4.mt.
GREEN CIRCLE BIO ENERGY produces 600,000 tonnes annually at Cottondale, Florida and exports from the Port of
Panama City on the USA Gulf Coast. It is one of the largest export wood pellets producers in the USA South, and one of the earliest having commenced production in 2008.
Deliveries on the 50-mile route are transported by dedicated rail cars on a short line rail service. Pellets are unloaded and stored in a 32,000 tonne-capacity flat bottom warehouse. Company exports about 30 vessels a year and have already dispatched 90 vessels since starting operations. Presently, all of its production is exported to Europe under shipping contracts tied to specific off-take contracts.
Green Circle executives believe that export volumes ex-USA will increase more than RISI estimates simply because the Europe 2020 mandate is far from having played out. The company is seeing other European countries such as Poland, Italy, and Spain emerge into the buyer realm, and once certain in-country issues are resolved in those countries, each could become large volume buyers of wood pellets sourced from the USA South.
Green Circle senior executives come from the international shipping industry, and have been able to leverage that experience and expertise into a highly efficient marine delivery programme for its customer base.
GEORGIA BIOMASS is owned by the German energy company RWE Innogy, whose business area is sustainable energy. With head office in Savannah, USA, Georgia Biomass has built up its production plant into one of the world’s largest manufacturers of wood pellets. Annual production capacity at its Waycross, Georgia facility is 750,000 tonnes, all of which is presently exported by marine vessels.
Product is railed to the East Coast Terminal in the Port of Savannah for marine transportation into RWE’s distribution network, and specifically to supply RWE’s Tilbury station (see above mention of Tilbury). Georgia Biomass ships under contract about 30 annual voyages from Savannah.
ENVIVA LP confirms production capacity of approximately 1.2mt per annum, with an additional 500,000 tonnes announced to come on line later this year. Production is at Ahoskie, NC and at two plants in Mississippi, and all current production volume is exported to Europe. Ahoskie production is delivered to Enviva’s owned terminal at Paradise Point in the Port of Chesapeake, adjacent to Hampton Roads,VA. The facility was acquired in 2011, and has annual throughput capacity of 3mt.
Enviva’s selection of Chesapeake is brilliant; it is geographically closer to Europe than other wood pellet export terminals, and leverages that location into decreased transport time and cost of freight. The terminal has 39 feet of available draught alongside and is long enough to accommodate Panamax vessels.
Two 48m-tall, 53m-wide storage silos receive, store and then load up to 90,000 metric tonnes of wood pellets to waiting vessels. The domes have systems for continuously monitoring and controlling temperature and fire prevention and detection. They can also withstand hurricanes and winds of up to 300+ MPH and an 8+ Richter scale earthquake.
At the Port of Mobile, USA, Enviva leases space in a strategic partnership with Cooper Marine. Enviva’s pellet manufacturing facilities in nearby Amory and Wiggins, MS, are situated along major inland waterways and highways that make transportation to the port easy and efficient. Pellets from the Amory facility are transported along the Tombigbee River and stored in barges until they can be loaded onto an ocean-going vessel. Pellets manufactured at Wiggins are transported to the port by truck. Enviva dispatches shipments of wood pellets every four to six weeks from the Port of Mobile.
FRAM RENEWABLES was established in October 2005 through the efforts of Per Arneberg, the Norwegian who is connected with the shipowning entities with the same Fram name. Fram Renewables produces 300,000 tonnes of wood pellets at Baxley, Georgia annually. Baxley is conveniently located on rail that can transport product to both Savannah and Brunswick for export loading. A second facility is due to come on line in 2013 at Hazlehurst, with annual production there of 500,000 tonnes. From Hazlehurst, export tonnage will be railed to the East River Terminal in the Port of Brunswick for loading onto Europe-bound vessels.
OTHERS. There are at least half dozen wood pellet projects announced for the USA South that would create additional production capacity of 2mt. At this writing, approximately 1.4mt is known to be for export. Many of these planned facilities are owned or controlled by European entities in the power generation sector. These facilities will be located in Texas, Louisiana, and Mississippi, and ports of loading will include Baton Rouge and Port Arthur.
In future, we should expect to see larger vessels transporting wood pellets, more vessels in-fleet that are CO2- fitted, more volume production that will appear in the trans-Atlantic, South America, and East Asia trade lanes, and more investment and supply chain management by consumers in the production of wood pellets in the USA South.
1. Green Circle Bio Energy, London
2. Norden A/S, Annapolis USA
3. DRAX Power Station, Selby UK
4. Enviva LP, Bethesda USA
WBMitchell Mitchell Consulting Group, Inc.
Cleveland Cascades Ltd – at the forefront of biomass loading solutions
Global manufacturer of loading chutes, Cleveland Cascades Limited, is seeing increased interest in biomass wood pellet applications, on top of another year of sales growth in 2012 that saw the company post record annual sales and be short- listed for two prestigious local business awards.
The Teesside-based (UK) company is well known for its shiploaders, silo loaders and road loaders for dry bulk materials such as potash, fertilizers and coal, with over 500 of these loading chutes already supplied throughout the world.
“So far this year, we have delivered silo loaders for soda ash to the USA, for sulphur to the UAE and for sulphates in Spain”, says Commercial Manager, Chris Wise. “In many ways, this is our core business, as these are the types of applications we have supplied over the past decades. We are, however, also seeing increased biomass enquiries for our Cascade Loading Chute. So far we have already supplied biomass chutes to UK power stations and the port of Tyne, however more recently we won an order for a shiploading facility in Canada. This demonstrates the versatility of the Cascade system, in that it can load huge volumes for sea freight from North American ports, but can also handle more specific loading, such as rail tanker loading when the biomass reaches the UK. Biomass wood pellets are being increasingly used as a renewable fuel source, predominantly as an alternative to coal. The loading of biomass wood pellets poses particular loading challenges however. Wood pellets are brittle and are prone to material degradation, therefore improper handling can result in increased dust emissions.
The material is also relatively low bulk density but needs to be handled in huge volumes to be economically viable. Wood pellets also have a lower calorific value than coal, which all means that the Cascade loading chutes need to be capable of handling large volumetric loading rates. This also means that silos need to be bigger and taller, meaning longer chute lengths. “This is something that we have encountered in the biomass projects we have already delivered. As in all our projects, our design teams worked closely with their client counterparts to develop the best possible solution to these issues.”
Traditional loading chutes that allow the freefall of material from conveyor to pile would result in high material velocity, subsequent material degradation and dust emission. The higher the loading drop, the greater the material velocity and the bigger the problems. This is avoided with the Cascade loading chute, as the material falls for a minimal distance from cone to cone throughout the length of the chute. As the pile height increases during the loading process, the chute is retracted, which allows greater pile heights and optimizes storage utilization in the vessel or silo.
The importance of biomass wood pellets as a source of renewable energy looks set to continue, with industry estimates of a threefold increase in demand by 2020. Cleveland Cascades recognizes this, and its staff recently attended a biomass training course at the renowned University of Greenwich Wolfson Centre for Bulk Solids Handling Technology.
This is part of the company’s proactive and innovative approach to bulk solids handling, which has resulted in continued sales growth and peer recognition in the upcoming North East Business Awards. “We have been shortlisted in two awards, the Export Award and Manufacturing Award” says Chris Wise. “It is a nice bonus to be recognized in this way, especially given the strength of competition in these categories.”
DSI: keeping dust at bay when handling biomass
Handling biomass fuel sources can easily create large amounts of dust from a variety of material handling systems. Dust Solutions Inc. (DSI) headquartered in Beaufort, South Carolina, USA, has many years of experience in dealing with these difficult dust sources, many in very dry and hot environments, some in very cold environments.
Large receiving hoppers such as truck tippers, loader dumps and grab hoppers are commonly used for the supply of wood waste, wood chips, sawdust, pellets and hog fuel. At the receiving hopper, the Dust Solutions Dry FogTM System works by injecting sub-micron water droplets into the dump pocket at the point of dust creation. The fog droplets attach to like size airborne dust particles as they try to escape the pocket. The slightly wetted particles agglomerate to other particles, creating sufficient mass to settle the dust back into the hopper. No chemicals are used and, unlike a dust collector, nothing is collected so no secondary waste stream is created.
For these dump pockets, DSI uses two stages of attack. Stage one fills the pocket with fog just prior to receiving the material. This ‘pre-fog’ supplies a reservoir of fog-charged air that when displaced by the falling material will scrub the air. As an example at a truck tipper, the fog manifolds at the dump hopper activate as soon as the tipper platform starts to rise.
Stage two is the same foggers continuing to operate during the complete dump cycle. This stage will attack the creation of additional dust at the dump as the truck continues to discharge fuel into the hopper. It is important to note that Dry Fog systems will not add any detectable moisture to the fuel, avoiding a BTU penalty normally associated with water sprays.
One of Dust Solutions’ latest biomass projects is the Nacogdoches 100MW generating facility in Texas, owned by Southern Company. This project was named Best Biomass Project for 2012 by Power Engineering Magazine. DSI provided Dry Fog dust suppression systems for the three truck tipper hoppers at this plant.
Conveyor transfer points can easily generate concentrations of dust that exceed safe limits for both respirable and explosive dust as well as contribute to exceeding fugitive dust limits. At these points, dry fog is injected into the covered conveyor head chute and at the receiving conveyor load point. If applied correctly, dry fog can achieve a zero visible emissions rating.
For ship and barge loading/unloading operations, DSI has modular fixed systems and portable systems that can fog at discharge chutes or across the ship hold to suppress dust that could enter waterways. It is important to note that, unlike water sprays with fans sometimes called fog cannons, dry fog will not wet the process material, only the airborne dust. Fan-like sprays use gallons per minute of water with 100 micron or larger droplets that are really defined as a mist or drizzle. Dry fog nozzles are rated in gallons per Hour and produce a 1–10 micron droplet size, true fog.
Preventing dust generation from biomass fuel storage piles is another important issue. DustTamerTM Wind Fence Systems are a much less expensive and often a more effective alternative to water sprays, chemical treatment, domes and buildings. The DustTamer system uses a specially designed fabric that can withstand winds in excess of 100mph. Its slotted design vs. a basket weave pattern helps prevent the fabric from plugging with fuel materials that can load up other fabrics. When fabrics like basket-weave-style shade cloth plug, the wind load becomes higher and the fabric will tear at some point.
DustTamer is resistant to the effects of UV rays, salt spray, and exhaust fumes. Some installations are approaching 20 years of service with no significant fabric deterioration. Additional benefits can include reducing the amount of air infiltration into a fuel storage pile that can contribute to spontaneous combustion. If water sprays are used at the pile, DustTamer can increase the time between applications times by slowing evaporation caused by air movement over the pile. Worker safety can be enhanced by reduction of airborne dust and fuel.
According to David Gilroy, sales manager for DSI, DustTamer is also used at truck dumps and loader hoppers in conjunction with the Dry Fog system to help contain the dust and fog in the hopper, combating the effects of both ambient air movement and displaced air from the dump.
In conclusion, each material handling situation requires careful evaluation to determine how to best approach the solution. DSI can assist in this evaluation and provide highly effective dust control measures for a variety of biomass material handling operations.
Flowing free with Standard Industrie products
Standard Industrie International designs and manufactures equipment that facilitates the storage, the free flowing, conveying and cleaning of powdery and bulk products, including major biomass commodity woodchips. Constant innovation is the motto of the company offering equipment to the latest technology and ever more efficient.
Founded in 1978, the company is now present around the world with subsidiaries in Europe, but also in South Africa, China, Canada and in Mexico. A new subsidiary just opened in the United States in order to increase the presence on the American Market.
The network of Sales Representatives Export is in charge of Eastern European countries, Asia, Central Africa, Middle East and Maghreb.
The company’s values are simple:
- professionalism: qualified teams ensure the installations as well as the maintenance activities;
- quality: certified ISO9001 and OHSAS1800 (internationally recognized), the company guarantees rigorous controls of the equipment; and
- Safety: Standard Industrie International always provides its customers with solutions ensuring the protection of their operators.
Standard Industrie International offers four ranges of products. Firstly Standard Industrie International is a major provider of solutions used for the declogging of silos and hoppers thanks to its air cannon, the AIRCHOC®, for which it has held a patent for more than 30 years. Its principle is simple: a volume of compressed air varying between 1 and 400 litres is released instantly. The effect obtained corresponds to a deflagration due to the sudden expansion of the compressed air. Today, the AIRCHOC®
enjoys an international reputation on the bulk handling market during these last thirty five years.
Committed to innovation, Standard Industrie International has developed the MACSYS®, an air cannon with several heads, perfectly suited for hot areas and difficult access. In order to better meet its customers’ needs, the company has developed a wireless version. Adaptable to the AIRCHOC® and to the MACSYS®, this innovative concept includes, as its name indicates, the installation of cable trays. With a control panel and a remote control, it is possible to remotely pilot up to 128 air cannons for optimum safety.
Currently, Standard Industrie International offers the widest range of air cannons on the market.
Standard Industrie International has also developed an efficient solution designed for conveyor belts to optimize their sealing property and safety: the LIFTUBE®. Also available in large width and high temperature versions, the LIFTUBE® ensures a reduction of dust emissions, loss of products, maintenance time and guarantees the safety of the operators.
Standard Industrie International also designs and manufactures equipment for industrial vacuum cleaning. Its know-how and expertise in industrial processes, completed by a personalized technical study, helps to provide the best cost effective technical answers to the applications whist ensuring a safe and healthy environment for operators.
From mobile units to vacuum trucks, Standard Industrie International offers all the configurations: from 3 to 300HP, electric or diesel, on container or on silo... whatever the cleaning needs.
Finally, Standard Industrie International offers cleaning services and declogging of hoppers and silos thanks to the GIRONET®. This mechanical cleaning is safe because it excludes any human interventions inside the silos and hoppers. In addition, through the use of compressed air and an aluminium housing around the engine, all risk of explosion is avoided.
Effective on any type of blockage, product or storage unit, the GIRONET® can be used without stopping production.Therefore, the customer can quickly recover its full storage capacity while ensuring optimum safety for its operators.
Standard Industrie International is committed to:
- providing innovative and tailored solutions to generate added value for customers;
- optimizing the manufacturing process;
- ensuring a working environment clean and safe; and
- reducing maintenance and production costs.
The distinctions of Standard Industrie International:
- designer and manufacturer;
- analysis and resolution of each customer’s problems;
- installation and maintenance of equipment;
- on-site products demonstrations; and
Standard Industrie International has emerged as a major worldwide provider of bulk handling solutions. This company, of French origin, operates in sectors as diverse as, power stations, steel plants, mines, quarries ... in order to give them all the necessary solutions regarding handling, production capacity recovery, working environment and safety.
VIGAN NIV 600 ship unloader: ideal for the handling of wood pellets
Major equipment supplier VIGAN has told Dry Cargo International that it is working actively in the biomass sector. The company acknowledges that the sector is still very busy, though it is likely that it is affected by current budget restrictions in many countries.
VIGAN is still receiving a number of enquiries regarding biomass handling equipment, some of which are still pending for final approval.
The company is working hard on ensuring that its technologies for biomass handling equipment are continuously improved. In particular, it is striving to maintain a global quality of its wear-resistant alloys, ensuring ease of maintenance. It is also working on guaranteeing a better match between global efficiency and energy consumption through more accurate measurements. All of VIGAN’s products comply fully with international safety and environmental regulations.
A CO-FIRING POWER PLANT PRODUCES MORE ECOLOGICAL ENERGY WITH WOOD PELLETS Alternative and renewable sources of energy are a major concern, not only due to limited resources of fossil origin but also within the context of worldwide efforts against gas emissions.
New power plants, as well as some existing energy producers, are upgrading their existing technologies with the latest innovations in order to fulfill their legal obligations of protecting the environment while containing costs.
The French group SUEZ is a major player in Europe and at worldwide level with about 200,000 workers and an annual turnover of more than US$110 billions. SUEZ has integrated this approach for many years with very significant investment in engineering developments and state-of-the art industrial installations. ELECTRABEL, the electricity division of the group developed a special project during the last few years for its power plant in Gelderland (city of Nijmegen in The Netherlands) with a capacity of about 600MW.
TRACTEBEL, its Belgian engineering affiliate, was in charge of developing this co-firing project (biomass + coal) by increasing by a factor of around ten (from 8tph [tonnes per hour] to 75tph) the incorporation of wood pellets up to a rate of 20% of the total energy produced by this upgraded plant. Since its operational start in 2010, this ELECTRABEL power plant has become one of the world largest co-firing plants with wood pellets.
Wood pellets are transported to ELECTRABEL plant by barges from various origins, thanks to the excellent hinterland river and canal system in the Netherlands for bulk transport. Nevertheless the discharge of such volume for a key sector requesting 24 hours per day reliability requires the highest quality and the most efficient operational performances.
VIGAN Engineering S.A., also a Belgian company specializing in pneumatic and mechanical ship-unloaders mainly for agribulk cargoes, with 40 years of experience and more than 1,150 items of equipment around the world, was selected to manufacture and install the pneumatic unloader for the barges of wood pellets.
PNEUMATIC UNLOADING OF WOOD PELLETS
The transport of any wood residue involves the challenge presented by the low density of those materials. Therefore, the most common process is pelletizing in order to condense them into granules (usually about 10–15mm in length and a diameter around 5–6 mm).
Thanks to this process and with a reasonable content of humidity, the wood pellets are quite free flowing and therefore easy conveying is possible from the production facility up to its use as an input in the power co-firing with coal.
During transport to the plant, those pellets can easily break and cause dust emissions: the use of grabs is not effective, due to major quay structural requirements, dust emissions, possible spillages than can be difficult and costly to clean up and, of course, low ‘through-the-ship’ efficiency when unloading small barges.
Pneumatic unloaders are known to be a more convenient solution for unloading barges, compared with grabs or mechanical unloaders. They offer:
- higher unloading rate mainly during the cleaning of the hold with the intake nozzle being able to suck down to the latest product particle on the hold floor but also to reach the hidden corners;
- safety: one operator is able to manage the whole unloading not only thanks to a remote control for all major displacements of the suction nozzle into the hold, but also by driving an auxiliary skid steer loader for even faster final clean-up;
- environment: no dust as the whole unloading system is under negative pressure and/or totally enclosed;
- no spillage and need to clean the surrounding quay; by optimizing the air and product speed
- minimum breakage in the pipes;
- low weight equipment with far less mechanical efforts on the quay structure.
The first pneumatic unloaders were manufactured at the end of the 19th century but continuous technological improvements have been introduced for higher reliability, better safety and optimum running costs.
VIGAN NIV 600 PNEUMATIC SHIP UNLOADER
To achieve those objectives, a VIGAN NIV 600 model in Gelderland has all the latest technologies available, such as the following as a few examples:
- three turbo blower groups (each four stages) with direct drive and controlled by latest speed variators (frequency inverters) by Schneider Electric. The direct drive is a major improvement because it reduces not only the numbers of bearings which are existing on traditional drive with belts but also the mechanical efforts on the turbine shaft. The multi-stage turbo blowers are maximizing the suction capabilities for a larger range of product characteristics to be handled with no need of any special feeding device and in combination with the speed control system, it make feasible to precisely optimize the energy consumption. Some VIGAN customers reported figures as low as 0.6 to 0.7kWh/tonne thanks to those technology developments and also chosen by ELECTRABEL. As also observed in this project, those three turbo blower groups are giving to the customer a convenient extra capacity of suction power reserve to face any unexpected event and to guarantee his daily unloading target.
- air jet pulse system for automatic cleaning of the filter. Widely recognized among the food and feed industry sectors for the global best performances and reliability, this system offers also a major ad-vantage about safety: no running mechanical parts are in contact with the air flow which could be eventually contaminated with dust and therefore could be the origin of explosion.
- major reliability and safety of this equipment are also due to special alloys against wear used for instance in the elbow between the vertical and horizontal suction pipes, in the airlock components and generally speaking by integrating most compulsive rules concerning latest European norms about engineering design, equipment manufacture and human resource protection.
The use of alternative sources of energy such as biomass will certainly increase during the coming years and all the logistic aspects of these inputs require very careful approach. Electrabel receives full credit for this landmark project in green electricity production. It also receives the credit for having understood the benefits of the pneumatic technology for a reliable and efficient unloader.