First dry ADIOX dioxin absorber system soon to go on stream
Adiox® is a state-of-the-art dioxin removal technology. Marketed and sold by Götaverken Miljö AB, Adiox material can be used to produce several types of components, such as tower packings, demisters (droplet separators) and dry fixed bed fillings. It has been installed in wet scrubbers at more than 50 full-scale incineration lines since its market introduction in 2002. Reference plants can be found in several countries in Europe including Germany, France, the Netherlands, Denmark and Sweden as well as in North America. This technology aims to:
- reduce or eliminate the ‘memory effect’ in wet scrubber systems with upstream dioxin removal
- improve the overall dioxin removal in combination with other technologies such as carbon slurry scrubbers
- meet the EU waste incineration directive with regard to emission requirements on dioxin to < 0.1 ng TEQ/Nm3, using Adiox as the primary dioxin removal system.
A wet scrubber system may also cost-efficiently be combined with a downstream semi-wet Adiox installation, where water-saturated flue gas is purified in an Adiox stage without continuous water circulation.
Having established itself in the wet scrubbing market, the use of Adiox in a dry environment is now being considered. When used in a dry absorber instead of in a wet scrubber, the removal efficiency is higher since the water film in a wet scrubber poses a mass transfer limitation for the dioxins. Less material is thereby required for the same removal efficiency, which leads to smaller equipment sizes. Suitable operational temperatures are 20°-40°C above the dew point, resulting in temperatures ranging from 60°C to 90°C.
The Swedish municipal power company Tekniska Verken Linköping AB has contracted Götaverken Miljö AB to outfit three of their municipal waste incinerators with a common dry Adiox absorber for dioxin removal. The maximum total flue gas flow is 186,000 Nm3/hour. The order is a breakthrough for Götaverken Miljö. The absorber has a diameter of nearly 7 metres and a total height of 15 metres. The contract was signed at the end of June 2006 and the plant will be operational by the end of 2006.
In summary, the advantages of the proposed new dry Adiox application are:
- more efficient dioxin removal per installed volume of packing
- a large volume can be installed in a single absorber section
- no requirement for process water circulation systems
- minimum requirements for electrical and instrument installations
- low requirement for regular access and maintenance, since the system is completely static
- as a consequence of the above, very high availability and economically competitive.
For more information, visit www.gmab.se or call +46 31 50 19 60
CHP for the Canary Islands
Cummins Power Generation designs, builds and maintains on-site power generation plants that produce electricity by harnessing waste fuels that have previously been ignored or disposed of in the environment where their impact can be costly.
An example of a combined heat and power (CHP) system manufactured by Cummins Power Generation can be found in the tropical Canary Islands. Waste management is a major problem for any populated area; however, it is especially critical for the islands because of their limited space and because tourism makes up more than 30% of their GDP. The disposal of solid waste is an environmental and political issue for the Canaries, a collection of islands totalling only 2875 m2.
One solution is the new Salto del Negro municipal waste treatment plant in Las Palmas de Gran Canaria. The plant processes waste collected from Las Palmas de Gran Canaria, a city of 380,000, as well as from several surrounding towns and villages. The waste is processed in a digester which produces methane gas, which is used in turn to fuel generators that produce both electricity and heat.
‘The Canary Islands are known for their unspoiled tropical beauty,’ says Jose Melgarejo, business development manager for Cummins Power Generation. ‘Most visitors aren’t even aware there is a waste treatment plant here, which is exactly what we wanted to accomplish.’
The primary purpose of the facility is to process the waste produced by the residents and visitors in Las Palmas de Gran Canaria and neighbouring cities. ‘The facility has a processing capacity of 200,000 metric tonnes a year. The capacity of the biogas digester is about 75,000 tonnes a year,’ says Melgarejo.
The plant is then able to use the biogas (65% methane) produced by the facility’s digester to power the cogeneration system. The CHP system uses the digester methane to generate both electric power and heat. The exhaust heat from the engines is used by the treatment plant to accelerate the anaerobic processes in the digesters, while excess electricity not used in the plant is sold to the local utility - earning a biogas-derived electricity premium.
The CHP system at the Salto del Negro waste management facility consists of two 1370 kW GQMA low-Btu gas generator sets, a PowerCommand® Digital Master Control and low-voltage switchgear, all built by Cummins Power Generation. These low-BTU generator sets are especially designed to run on dilute solutions of bio-derived methane gas produced by municipal landfills, sewage digesters and coal seams. A third generator set is scheduled to be added within a year. In addition, Cummins Power Generation supplied all of the system’s ancillary equipment such as radiators, heat exchangers and expansion tanks, and provided installation supervision and commissioning.
For more information, visit: www.cumminspower.com/energysolutions, or call +44 1843 255000.
BWV optimizes thermal performance
Babcock & Wilcox Vølund is a leading supplier of technology for converting household waste and biofuels into thermal energy. Recently it has developed a new cast-iron water-cooled grate which offers full integration with the air-cooled grate, providing complete freedom within the grate area, be it air-cooled, water-cooled, or both.
Advantages of this approach include:
- cooling water is an integrated part of the shafts holding the grate bars - that is, no pipes/tubes are required under the grate
- no grate bar damage due to temporary cooling system failure
- grate surface cooling is independent of combustion; air can thus be added and adjusted for optimal combustion
- strong agitation (mixing) of the waste fuel, ensuring efficient combustion and very low levels of unburnt carbon in the bottom ash.
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In addition, BWV is upgrading its technology to improve thermal performance, by injecting secondary air into the combustion zones at multiple places at different angles and air velocities. The technology helps achieve maximum operation life, low emissions and high thermal efficiency. The system, named VoluMix™, is designed on the basis of computational fluid dynamics (CFD) modelling. Its advantages include:
- good mixing in the furnace
- reduced temperature peaks in the furnace for minimum thermal NOx formation
- staged combustion makes it possible to reduce the formation of fuel NOx
- avoidance of hot spots in the furnace and boiler which would speed up corrosion
- obtaining turbulent conditions in the throat for optimum burn-out
- even temperature and velocity distribution in the passes in order to maximize heat transfer and residence time.
For more information, contact Ole Hedegaard Madsen at Tel: +45 4326 5859
SC Technology offers low-temperature belt drying
SC Technology GmbH (SCT) has successfully concluded a global technology license agreement with Lindauer Dornier GmbH of Germany. Dornier has been designing and building belt driers for a wide range of applications for more than 50 years. SCT has been a leading name in the sludge industry for the past 25 years designing, building and operating sludge driers around the world.
SCT is now poised to build on its strong position in the market and introduce this new low-temperature belt-drying product. Backed up by eight years of practical experience (56,000 operational hours), SCT maintains a leading position in the European sludge-drying industry through a combination of:
- high-quality construction materials
- patented design elements providing clear process benefits
- continuous process and economic development
- operational experience in seven European countries.
While known globally for its drum-drying technology, it is the European market that drives SCT’s product development and determines the range of services offered.
Over the past three or four years, the European sludge drying market has changed significantly. Historically the market demanded that sludge drying produce a high-quality granule suitable for easy disposal, primarily to agriculture. This has now been replaced by waste heat utilization and disposal in power stations and cement kilns.
Formerly, the rotary drum drier was the technology of choice to achieve high-quality dried sludge granules for land application, but as this type of application has been prohibited through legislation changes in many European countries, thermal disposal in power stations and cement kilns has become the predominant outlet for dried sludge.
This significant change, along with the widespread use of waste heat, has moved the industry away from burning fossil fuels. Volume reduction at the lowest cost has become the order of the day.
High-temperature (about 400°C) rotary drum drying does not lend itself easily to such a market and technology that operates at lower temperatures (100°-150°C) with a much longer residence time is now in demand. For these reasons, SCT is pleased to offer the new low-temperature, belt-drying solution.
For more information, contact info@swisscombi.com, call: +41 62 888 0 888 or visit www.swisscombi.com
Electric actuation: a growing choice for WTE plants
Electric actuators in waste-to-energy plants control the position of dampers and vanes which improve the efficiency of and reduce the emissions from furnaces. They also control the valves in the steam and water circuits that drive the generators.
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The implementation of mandatory environmental directives throughout Europe has been proved to be a major catalyst for actuation upgrade programmes. For example, the European Large Combustion Plant Directive (LCPD) demands accurate control of final operating elements including secondary air dampers, burner shroud and fan vane controls. Furthermore, schemes such as boosted over fire (BOFA), separated over fire (SOFA) and over fire air (OFA) have encouraged major investment in this area.
High-speed electric actuators for continuously modulating duties are now able to meet the arduous operating requirements set by these regulations, whereas in the past hydraulic power packs were generally used. The advantages of electric actuation in these areas include reduced capital, operating and maintenance costs, improved control and increased reliability.
Electric actuators may be required for an extensive range of duties encompassing isolation, regulation, modulation and fail-safe operation of valves and dampers, so in today’s industries it is essential to select the correct specification for the actuator and control system for each duty.
Developments in electric actuator design have introduced secure, ‘non-intrusive’ water and dust-tight enclosures. Standardized electronic actuator controls and a wider range of torque outputs also helped the design engineers. In addition, improved motor controls and the introduction of thyristors (rather than traditional reversing starter controls) increased the ‘starts per hour’ performance of the electric actuator, enabling it to be used for many regulating and modulating duties. (A thyristor is a solid-state semiconductor device that acts like a switch and is particularly suitable for frequent operation, offering a reliable and maintenance-free alternative to traditional electro-mechanical switches.)
In the last 10 years, these developments have dramatically accelerated with the introduction of high-temperature modulating duty actuators. This is a major leap forward, enabling electric actuators to be installed in environments where hydraulic and pneumatic actuators were traditionally specified. This has been a welcome improvement, since hydraulic systems incorporating traditional power packs and hydraulic rams have become unpopular due to high maintenance costs and the threat of oil leaks leading to secondary damage or even fires in boiler areas. Instrument air for pneumatic actuators is also expensive to produce and look after, with leakage, water ingress and vulnerability to freezing all threatening reliability and requiring special attention.
Suitable for isolating or modulating duties, electric actuators provide a simple, reliable solution and eliminate the need for secondary compressor or hydraulic systems with complex control and instrumentation. As many plant operators look to upgrade their control systems - enabling improved communication with advanced plant management systems - it is not surprising that many are turning to this technology.
For more information on Rotork Controls Ltd, Tel: 01225 733200, e-mail: mail@rotork.co.uk, www.rotork.com
Thermoselect expands in the US
Thermoselect has licensed its solid waste gasification technology to Interstate Waste Technologies (IWT) for the US and Caribbean territories.
IWT and the Thermoselect technology have been qualified and placed on ‘shortlists’ by experienced US-based engineering companies such as URS, HDR and Alterative Resources, Inc. (ARI), working on projects for Waste Authorities in Puerto Rico, Los Angeles County, New York City, a separate project for the City of Los Angeles and in north-east Maryland. IWT and Thermoselect were ranked first in both Los Angeles procurements as well as the New York City procurement and were judged qualified for the north-east Maryland project.
IWT’s Caguas, Puerto Rico project a 3240-tonne-per-day waste-to-energy facility - is furthest along in the development process. The project has been approved by the Puerto Rico Solid Waste Management Authority. It includes nine Thermoselect processing modules, each with a rated capacity of 360 tonnes per day. IWT plans to use the synthesis gas produced by the Thermoselect process to generate electricity in a gas turbine combined-cycle system.
The Thermoselect technology easily satisfies the US EPA air emissions criteria and significantly reduces dangerous greenhouse gas emissions. In addition, the technology is viewed favourably by US waste management authorities because there are no discharges of process water. The ability of the technology to recycle 100% of the waste is particularly important in an island setting such as Puerto Rico, where it is difficult to site new landfills, especially in the northern part of the island due to its limestone subsurface condition.
The size of the Caguas project, along with the higher avoided cost for electricity in Puerto Rico (due to the fact that 83% of it is oil-based), has enabled IWT to offer a tipping fee competitive with the cost of landfilling waste on the island.
IWT and Thermoselect are conducting a detailed study to confirm the feasibility of using synthesis gas generated in the Thermoselect process to manufacture alternative liquid fuels, such as ultra-clean diesel for a project in New York City. Approximately 26 gallons (98 litres) of clean diesel can be produced from each tonne of waste processed. New York City currently collects and disposes of approximately 11,500 tonnes per day of municipal solid waste. The clean diesel approach would enable the City to solve a portion of its solid waste problem, use the clean diesel in its buses and trucks to significantly reduce air pollution, while obtaining a long-term supply of diesel fuel at a cost independent of the cost of oil.
IWT’s efforts have been helped by the success of Thermoselect’s licensee in Japan - JFE. JFE currently has seven facilities operating on a commercial basis using Thermoselect technology. This experience has provided evidence to waste management officials and consultants worldwide of the ability of the Thermoselect technology to process waste in a reliable and sustainable manner.
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For more information, contact: Dr Wulf Kaiser, www.thermoselect.ch, Tel: +41 91 7562525; Mark Augenblick, www.interstatewastetechnologies.com, Tel: +1 540 6873177
European BREFs on waste incineration and waste treatments formally adopted
The Integrated Pollution Prevention and Control (IPPC) Directive (EC/96/61) requires EU Member States to ensure that industries falling within its scope are issued with a permit based on the concept of ‘Best Available Techniques’ (BAT). In order to facilitate the implementation of the IPPC Directive, the European Commission organizes an ‘exchange of information’ on the subject of Best Available Techniques (BAT) between experts from the EU Member States, industry and environmental organizations. The main outputs from this information exchange are the BAT Reference Documents (BREFs).
The BREFs on waste incineration and waste treatments were formally adopted by the EC as guidance on BAT under the IPPC Directive in August 2006. They provide a regulatory benchmark for the waste sector in addition to the controls set in existing legislation.
For most installations burning wastes, the European Waste Incineration Directive (EC/2000/76) (WID) sets controls on releases to water and air, by setting emission limit values and establishes certain operating standards in relation to combustion conditions and residue quality. Transposition into the national legislation of EU Member States was necessary by 28 December 2002. From this date on, all new incinerators have had to comply with the provisions of the WID. The deadline to bring existing plants into compliance was 28 December 2005.
Achieving WID standards does not automatically mean that the requirements to use the Best Available Techniques (under IPPC) have been fulfilled. In legal terms it is the WID that provides the minimum performance standards. However, it is anticipated that the application of BAT and an ‘integrated approach’ will result in further improvements in operational standards. Looking forward, industries under IPPC in most EU Member States should have a permit based on BAT by October 2007, which is the deadline set in the IPPC Directive.
For more information, visit www.eippcb.jrc.es or contact Paul James at paul.r.james@aeat.co.uk. He is the leader of the international expert technical working group that produced the BREF on waste incineration.
Eswet Welcomes the Revised Draft of the Waste Framework Directive
In the draft of the revised European Waste Framework Directive, currently under debate, the European Commission recognizes the benefits of waste-to-energy (WTE) by admitting for the first time that WTE can be considered as ‘recovery’. The association European Suppliers of Waste-to-Energy Technology (ESWET) welcomes this change in policy and actively strives to further the advantages of this technology by promoting higher energy recovery from MSW and reuse of the residues from combustion.
Founded in March 2004, ESWET co-operates with other national and international organizations active in this field. As of today, it has 10 member companies based in five different countries in Europe. ESWET members hold a world-leading position in this innovative technology, which has its roots in Europe and has been exported to all regions of the world.
The main purpose of ESWET is to foster the development and the dissemination of WTE technology. With this in mind, the association seeks to promote:
- awareness of the positive implications of the technology concerned
- exchange of experience between its members and the European administration
- plant safety
- environmental compatibility and social acceptance of plants.
Through activities related its goals, ESWET participates in the elaboration of new directives, regulations andstandards on the European level.
WTE technologies effectively concentrate pollutants contained in MSW and remove them from the eco-cycle. Due to the most stringent limits for permitted emissions to air, the contribution of MSW plants to overall pollution is very small. Materials such as metals and bottom ash can be reused. Most importantly though, the energy contained in the MSW can be recovered in a steam boiler, with the steam either used as process steam, in district heating networks or to generate electricity. This is becoming an ever more important advantage today, with not only growing energy prices but also a foreseeable scarcity of primary energy sources such as oil, gas and coal.
ESWET strongly believes that WTE technology is an integral part of an overall sustainable waste management scheme, utilizing the energy contained in the residual MSW after all technically and economically viable efforts of waste avoidance, reduction, reuse and recycling have been made.
The still widely used practice of unprotected dumping of MSW in a landfill has many environmental disadvantages. Pollution of soil and groundwater, uncontrolled emissions of gases (such as CO2 and CH4 which contribute to global warming), and the need for long-term surveillance are just some of the substantial drawbacks of conventional landfilling.
