2007
Paper written by Bart Adams, Elisabeth Prasman, Renaat De Proft, Bart Van Renterghem - Keppel Seghers
Presented at the 'waste to energy' conference, Bremen (Germany), 9-10 May 2007
ABSTRACT
As a result of the intensified focus on the sustainability of waste management, a marked increase in the demand for Waste-to-Power (WtP) plants fueled by municipal solid waste (MSW) and more specifically refuse derived fuel (RDF) with high energy recovery efficiency has been observed during the last decade. Often, this tendency was stimulated by governmental support programs with dedicated subsidies for facilities with increased energy recovery rates. Perhaps the most striking example constitutes the soon to be completed revision of the Waste Framework Directive (WFD) in which the distinction between a ‘recovery’- and a ‘disposal’-operation is linked to this very energy recovery efficiency. Although the energy recovery rate is readily and substantially increased in case of a combined heat-and-power (CHP) application, a suitable utilisation of the produced heat within the plant’s vicinity is often lacking such that only electricity is generated. The current paper deals mainly with this type of facilities.
Common technical measures to increase the electricity production of a WtP in the design phase include: lowering the boiler exit temperature, operating at lower air excess, reducing the pressure at the turbine exit, using steam re-superheating and multi-step expansion, and increasing the steam parameters (temperature and/or pressure). Although other possibilities are known and have been applied on an industrial scale, they are considered either too dependent on local conditions or not sufficiently significant (i.e. only a marginal increase in efficiency is realized).
A concise review of the available experience with each of the aforementioned options is presented by means of actual data from existing industrial facilities. It is shown that the last option (higher steam parameters) in particular tends to lead to increased boiler wear. In order to compare the benefits and drawbacks of each option and allow a sound design of a new facility, a full life cycle cost analysis is presented including a clear indication of all main assumptions. The gate fee, the electricity price, the lifetime of essential boiler components and the plant’s availability are used as parameters in a sensitivity analysis.
2006
Article written by Bart Adams, An Raveel, Tom Spooren - Keppel Seghers ; Gerrit Du Toit - SITA Waste (Isle of Man) ; Peter Waller - Aker Kvaerner Engineering Services
Published in Environmental Progress, Volume 25, Issue 3, October 2006
ABSTRACT
Semiwet scrubbers are used for the removal of acid components from flue gases in a variety of thermal processes. The focus of this study is application of the technology in the recently commissioned municipal waste incinerator of the Isle of Man, characterized by considerable variations in the pollutant concentrations and the gas flow rate.
The concept and principles, the design procedure, and the performance of the scrubber are discussed. The latter is illustrated by means of detailed operational data over extended periods. Special design features include adjustable guiding vanes in the diffuser, advanced temperature control for optimum removal efficiency, and advanced lime-dosing control for minimal reagent consumption.
Long-term results indicate that the scrubber allows continuous operation below the current EU emission limit values for acid gas components (averages of 8 mg HCl per Nm3 and 14 mg SO2 per Nm3). Furthermore, operation and maintenance experience indicates optimal spray pattern control, illustrated by low moisture content of the residues (average of 2%), no handling or transport problems, and the total absence of lime caking on the reactor walls. Finally, the influence of operational parameters such as the reaction temperature and the inlet pollutant level are shown by means of industrial-scale measurements in the reference plant.
Paper written by Bart Adams, Renaat De Proft, Marc Van Craen - Keppel Seghers
Presented at ISWA/DAKOFA Annual Congress 2006, Copenhagen (Denmark), 1-5 October 2006
ABSTRACT
Due to the overestimation of the demand and the capacity for co-combustion of RDF and the boom in mechanical biological treatment facilities in the last few years, a surplus of this type of fuel has been noted on the German market. Similar situations can be expected in other member states of the European Union in the near future.
On average, RDF has a higher heating value (11 – 18 MJ/kg and even higher), a smaller particle size, and a lower bulk density and ash content than untreated waste. Increased concentrations of pollutants such as chlorine, sulphur and heavy metals have been observed. A wide array of RDF types is available on the market and even for one particular pre-treatment system, the composition and properties of the pre-treated waste can vary wildly.
The particular characteristics of RDF necessitate a dedicated incinerator design, different from that of a WtE facility for untreated waste. Furthermore, a simple analysis of the revenue distribution of a RDF facility indicates that specific measures to boost the energy recovery efficiency are justified. The proposed RDF Power Plant concept is based on the Keppel Seghers’ Water-Cooled Grate and Boiler Prism. The combination of both technologies allows operation at reduced air excess ratio without adversely affecting the combustion quality or increasing the risk on high-temperature boiler corrosion. Theoretical modelling shows that the gross electricity efficiency can be increased from 22-24% for a conventional WtE plant to 26-27% for an RDF plant with only a marginal increase in investment level. A high performance flue gas cleaning system is used, relying on a lime based semi-wet scrubber complemented with sodium bicarbonate injection.
Life cycle analyses indicate that the proposed standard RDF concept (low air excess ratio, increased steam boiler pressure) is very competitive for the current gate fees and electricity prices. The advanced RDF concept (even higher steam boiler pressure and steam re-superheating), is only competitive in case of particularly favourable electricity prices.
Paper written by Bart Adams, Renaat De Proft, Marc Van Craen - Keppel Seghers
Presented at Clean Power 2006, Lahti (Finland), 6-7 September 2006
ABSTRACT
A marked increase in the demand for waste-to-power (WtP) plants for high calorific fuels such as refuse derived fuel (RDF) has been observed in the last few years. Clearly, this trend is linked to the growing popularity of waste pre-treatment systems such as mechanical biological treatment facilities. Even more so than for WtP plants on untreated waste, RDF plants are geared towards high energy recovery and electricity production rates.
Similar to biomass, RDF properties vary wildly and depend heavily on its origin, i.e. type of pre-treatment. Typical ranges of physical, mechanical and chemical characteristics of RDF are discussed in the first part of the paper. Generally, RDF has a higher calorific value and an increased chlorine and sulphur load than untreated municipal solid waste. This, together with the goal of high energy recovery, necessitates special design features for RDF facilities.
The second part of the paper focuses on the furnace and energy recovery boiler of the RDF plant. A technical and a life cycle cost analysis (LCC) is presented to support the use of a water-cooled grate and the proprietary secondary air prism. A concise discussion of the main features of both technologies is included. Next, different steam-condensate cycle options as well as different protective measures against corrosion are compared by means of a technical and a LCC analysis. The main parameters are identified and, among other options, the use and impact of elevated steam conditions and/or resuperheating is discussed.
Using the same approach (i.e. technical & LCC analysis), different flue gas cleaning options are discussed in the third part of the paper. Mainly semi-dry and dry systems with and without residue recirculation and additional reagent injection (sodium bicarbonate or high performance lime) are considered.
Based on the above analyses, the optimal concept for an RDF WtP plant is presented in the last part of the paper.
Paper written by Bart Adams, Tony Clark - Keppel Seghers ; James Heath - Cyclerval UK ; Gerrit Du Toit - SITA (Isle of Man) ; Peter Waller - AkerKvaerner Engineering Services
Presented at WASTE 2006 - 5th annual symposium on waste treatment technologies, Paignton (UK), 12-16 June 2006
ABSTRACT
Most recently built waste-to-energy (WtE) plants are equipped with either a semi-wet or a dry scrubbing system for the removal of acid components from the flue gases. The paper compares both systems in terms of technology, investment cost, and operational expenses. In addition, the paper reviews practical operating experience with both systems. For this purpose, two recent case studies are presented.
The Isle of Man-plant has been treating the island’s non-recyclable waste since February 2004. It comprises two lines, a primary one for the processing of municipal waste (65,000 TPA) and a secondary line for the treatment of clinical waste and animal carcasses (6,000 TPA). Both are equipped with semi-wet scrubbing systems (55,000 Nm³/hr and 14,500 Nm³/hr, respectively) and have shown reliable and efficient operation within the European Waste Incineration Directive’s emission limits.
Up to 56,000 TPA of municipal waste is processed by the single incineration line of the WtE-plant in Grimsby. The flue gas cleaning system is based on a DRY SCRUBBER, which is designed for an average flow rate of 41,000 Nm³/hr. The plant has been in operation since mid-2004 with excellent results in terms of stack emissions.
By a detailed analysis of the engineering, construction, commissioning and commercial operation of the flue gas cleaning systems in both projects, the characteristics of the semi-wet and the dry scrubber are reviewed. In addition to technical aspects such as operating conditions, removal efficiencies and consumptions, the economic side is also presented. Long-term operational data of both plants are used to illustrate the performance of the systems. Furthermore, practical operating experience is reviewed.
Based on the previous comparison, the relevant criteria for selecting the optimal flue gas cleaning system for future projects are discussed.
2005
Paper written by Quentin Olivier, Bart Adams and Bart Van Renterghem - Keppel Seghers
Presented at 10th European Biosolids and Biowastes Conference, Wakefield (UK), 13-16 November 2005
ABSTRACT
Treating wastewater of large cities constitutes a critical step in meeting the clean water demand worldwide. With the number of wastewater treatment plants (WWTP) steadily rising in many countries, safe, flexible and cost-efficient treatment technologies for the produced sludge are needed.
First, the paper provides an overview of existing treatment routes, opportunities for re-use and current market trends in function of the sludge characteristics and other relevant parameters. Particularly the new trend for the use of sludge as renewable energy is discussed.
Next, a series of proven industrial solutions is reviewed by means of case studies on projects in large urban centres such as Barcelona, Bruges, Antwerp, Baltimore, Chicago, and Copenhagen. Specific operating and safety features, the environmental impact of the facility and the public and governmental perception of the technology are highlighted.
Finally, the advantages of an integrated water and sludge treatment approach is discussed.
Paper written by Bart Adams - Keppel Seghers ; Mark Périlleux - MAPEC
Presented at 2. Freiberger Diskussionstagung “Rauchgasseitige Dampferzeugerkorrosion”, Freiberg (Germany), 27-28 October 2005
ABSTRACT
For many MSWI-plants, high-temperature corrosion represents the single largest expense in their yearly operations & maintenance budget. However, the effect of this type of corrosion can successfully be minimized by adapting a proper design strategy. The latter is aimed primarily at obtaining moderate flue gas velocities and intense mixing in the first radiation pass, realizing a uniform flue gas flow pattern, and ensuring an optimised temperature profile throughout the boiler. In medium-large furnaces (> 40 MWth), the Keppel Seghers’ BOILER PRISM forms a key component in the aforementioned design strategy. Special attention will be directed to the explanation of the operation of this component, complemented with long-term operational data from several industrial scale reference plants.
Editorial written by Bart Adams – Keppel Seghers
Published in Waste Management World, Issue November-December 2005
The last few years have seen a marked increase in the demand for waste-to-power plants for high calorific fuels such as refuse derived fuel (RDF). This evolution is mainly driven by the growing popularity of waste pre-treatment systems relying on mechanical biological treatment or similar processes.
Keppel Seghers responded to the growing demand by further developing and combining two of its key technologies into a novel combustor concept. The optimal integration of Keppel Seghers’ WATER-COOLED GRATE and its BOILER PRISM constitute the core of the new incinerator type. The main advantages of the new concept include increased energy efficiency, higher availability and lower operating costs.
2004
Paper written by Olvier Pollet, Peter Van De Moortel, Quentin Olivier – Seghers Keppel Technology ; Wim De Ryck, Johan Van de Velde – Aquafin
Presented at 9th European Biosolids and Biowastes Conference, Wakefield (UK), 14-17 November 2004
ABSTRACT
The Antwerp (Deurne) sludge drying/pelletising plant has been in successful continuous operation for five years and is an important installation for the overall sludge disposal strategy of Aquafin in Flanders (Belgium).
This paper will first explain the context of sludge disposal in Flanders, and how the Antwerp plant contributes to solve part of this problem in a sustainable way.
It will then analyse the operational and maintenance results of 5 years operation of the plant. The following items will be more specifically discussed :
- Operation and maintenance :
- yearly throughput
- plant availability and reasons for shut-down
- activities of the operators
- Energy :
- thermal energy balance of the different components of the plant
- power consumption of the different units of the installation
- Possible improvement of the installation in order to improve its O&M performance.
Finally, this paper will discuss the benefits of using biogas as an energy source and dried sludge pellets as a green fuel for cement kilns, co-incineration with sludge cake and coal power plants.
Paper written by Bart Adams, Kris Peeters – Seghers Keppel ; Herman S.W. Diederen, Jac P.F. Wijnhoven - Afvalverbranding Zuid-Nederland (AZN)
Presented at ISWA 2004, Rome (Italy), 17-21 October 2004
ABSTRACT
Cost analyses of waste-to-power plants (WtP) indicate that often more than one third of the maintenance budget is spent on high-temperature boiler corrosion. Based on the understanding of the main corrosion mechanisms, the Keppel Seghers BOILER PRISM as a primary measure against corrosion is explained. The results of more than 15 years of operational experience are reviewed.
From 1997-1999 the Bonn WtP plant (3 x 29MWth, 400°C / 40bar) was retrofitted with boiler prisms. In 2001, a boiler prism was installed in the WtP of Moerdijk (3 x 81MWth, 400°C / 100bar) as an essential part of a revamping program. After more than one year of observation, the remaining two lines were also revamped.
The performance of the Keppel Seghers BOILER PRISM has been assessed by means of on-line equipment and dedicated measurement campaigns. Additional operational benefits have been quantified.
With respect to the Moerdijk WtP plant, the following effects have been identified:
- a decrease in corrosion rate of the first pass boiler roof by more than a factor five,
- an increase in time between shutdowns by a factor 1.5,
- an 8% increase in throughput,
- a 6% increase in availability, and
- a strong reduction in ammonia and natural gas consumption.
Based on the above, the pay-back period was calculated as 3.1 year.
Article written by Bart Adams, Kris Peeters - Seghers Keppel ; Herman S.W. Diederen, Jac P.F. Wijnhoven - Afvalverbranding Zuid-Nederland (AZN)
Published in Waste Management World, Issue September-October 2004
ABSTRACT
High-temperature boiler corrosion is a frequent cause of shutdown in waste-to-energy plants and therefore must be combated. An innovative device, the Seghers BOILER PRISM, has been showing impressive results in reducing corrosion at the Bonn and AZN plants.
Paper written by Bart Adams, Kris Peeters, Dirk Eeraerts - Seghers Keppel ; Herman S.W. Diederen, Jac P.F. Wijnhoven - Afvalverbranding Zuid-Nederland (AZN)
Presented at NAWTEC 12, Savannah (USA), 17-19 May 2004
> Seghers Keppel & AZN received an award for the price for the Best Paper among more than sixty other contenders.
ABSTRACT
This paper contains novel insights regarding the operation of the Seghers BOILER PRISM and its effectiveness as a primary measure against high-temperature boiler corrosion in waste-to-energy (WtE) plants. Since the previous presentation at NAWTEC 10 in 2001, three additional boiler prisms were successfully commissioned as a retrofit at a large WtE facility in the Netherlands (3 x 705 tonnes/day at 4,700 BTU/lb; 110 tons/hour steam at 1,450 psi, 750°F).
The main data and experience of the retrofit project in the Netherlands are discussed and results regarding the performance of the Seghers BOILER PRISM are presented in detail. The latter are based both on existing process monitors as well as dedicated measurement campaigns and include:
- temperature and oxygen distribution in the 1st radiation pass,
- feedback on corrosion rates,
- influence on the combustion quality, and
- impact on the effectiveness of the mechanical cleaning equipment.
The results confirm the effectiveness of the prism as a primary measure against high temperature boiler corrosion and highlight the additional operational benefits.
2003
Paper written by Ubrik Janses, Olivier Pollet, Quentin Olivier - Seghers Keppel Technology
Presented at 8th European Biosolids and Biowastes Conference, Wakefield (UK), 23-26 November 2003
ABSTRACT
Since July 2003 all new and existing drying plants in Europe will need to comply with the European ATEX directives.
This paper describes the specific requirements for drying plants towards the ATEX 95 directive (directive 94/9/EC), concerning equipment and protective systems intended for use in potentially explosive atmospheres, and the ATEX 137 directive (directive 1999/92/EC), concerning the minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres.
Comparison is also made with the US NFPA 654 standard for the prevention of fire and dust explosions from the manufacturing, processing and handling of combustible particulate solids.
Measures to be taken in line with the directives will not only influence the design and build of drying plants but will also directly involve responsibility of the employer and owner of the drying plant.
A case study further illustrates the specific measures to be taken in a tray dryer/pelletiser system.
Paper written by Ubrik Janses, Olivier Pollet, Quentin Olivier - Seghers Keppel Technology
Presented at 8th European Biosolids and Biowastes Conference, Wakefield (UK), 23-26 November 2003
ABSTRACT
At the light of a recent industrial realisation, this paper examines in detail the solution of a sludge fluidised bed combustor combined with a dryer-pelletiser.
The calorific value of mechanically dewatered sludge is often not sufficient in order to sustain a fully auto-thermal combustion process. Therefore, sludge combustion processes either require partial thermal drying of the sludge, the use of high calorific waste (e.g. RDF) or an additional fossil fuel source (e.g. coal) to sustain the combustion. It is also possible to install a sludge pelletising process prior to the fluidised bed combustor. Sludge hard pelletising results in hard and round pellets that are easy and safe to store and handle. Combining sludge fluidised bed combustion with hard pelletising results in a better energy balance and offers higher flexibility.
The Bruges plant manages sewage sludge from the Bruges WWTP and from most other WWTP in the West part of Flanders, the Northern part of Belgium. The paper discusses the fundamental principles for selecting the co-joined thermal processes, as well as its operating history, public and governmental perception of the technology, and decision to continue with the technology and increase its capacity.
The Bruges sludge incineration facility was commissioned in 1985. It uses two of Seghers proprietary technologies: the ZEROFUEL fluidised bed combustor, specially designed for low calorific wastes, and the HARDPELLETISER: The Pearl Process®, an indirect heat dryer and pelletiser for biosolids. A retrofit of the plant resulting in a capacity increase of 40% has been decided in 2000 and successfully implemented in just 14 months. The basic principle of the retrofit was that the existing fluidised bed combustor could process more sludge (i.e. more dry tonnes per year) if more water was removed from the sludge before introduction in the furnace. It involved the installation of a new HARDPELLETISER with a much larger treatment capacity and important changes in the energy recovery system in order to be able to run the facility auto-thermally, without any additional fossil fuel.
The paper presents the main technical aspects of the Bruges plant, including sludge mechanical dewatering, materials handling, sludge pelletising, fluidised bed combustion, energy recovery, safety features, and emissions. As additional external fuel sources are not required for the combined process, this case study also highlights the concept of a “zero-fuel” plant.
Article written by Patrick Smits - Seghers Keppel
Published in Kluwer Nieuwsbrief Milieutechnologie, Editie September 2003
In Vlaanderen is er nog steeds een tekort aan verbrandingscapaciteit voor huishoudelijk afval en eraan gelijkgesteld bedrijfsafval. Voorbehandeling van het ingezamelde restafval, waardoor de brandbare fractie verkleind kan worden, lijkt daarom een interessant alternatief.
Ook voor landen die nog maar weinig vorderingen hebben gemaakt met de selectieve inzameling van afval biedt voorbehandeling meerdere voordelen. Dit artikel bespreekt de DANO-technologie, een continu-proces voor afvalvoorbehandeling waarvan de basis reeds in de 30-er jaren werd gelegd.
Report written by Quentin Olivier - Seghers Keppel Technology ; C.M. van der Meijden, J. Hanse, M. de Graaf, A. Bos, H.J.M. Visser - Energieonderzoek Centrum Nederland
Dit onderzoek is uitgevoerd in het kader van het NOVEM-DEN programma.
Published in May 2003.
ABSTRACT
Sinds de recente BSE-crisis mag diermeel niet meer worden verwerkt in veevoer. Momenteel wordt deze afvalstroom opgeslagen, maar dit brengt hoge kosten en grote risico’s met zich mee. Een manier om diermeel te verwerken is de verbranding van dit afval in een wervelbed. Om na te gaan of deze optie technisch mogelijk is, heeft het Energieonderzoek Centrum Nederland (ECN) samen met de Belgische technologieleverancier Seghers een testprogramma opgezet en uitgevoerd. Tijdens een duurtest van 150 uur werd gekeken naar mogelijke technische knelpunten zoals bedagglomeratie, vervuiling van de warmtewisselaar en uitstoot van rookgassen. Na de test bleek dat deze problemen niet optraden bij de verbranding van diermeel.
Op basis van de duurtest concluderen de onderzoekers dat verbranding van diermeel in een wervelbedinstallatie een goede optie lijkt voor het verwerken van de problematische afvalstroom. De bij de verbranding vrijkomende warmte kan worden benut voor het maken van processtoom of de productie van warmwater. Hierdoor beschikt een commerciële installatie, die met dezelfde procescondities wordt bedreven als in de duurtest, over een thermisch rendement van circa tachtig procent.
Paper written by Bart Adams, Dirk Eeraerts, Ivan Christiaens – Seghers Keppel
Presented at NAWTEC 11, Tampa Bay, Florida (USA), 28-30 April 2003
ABSTRACT
In 2001, Seghers was awarded the contract for the design and construction of the furnace and heat recovery system of a new, 330 tons per day WtE-plant in Orebrö, Sweden. A wide variety of municipal and industrial wastes (including electronic waste, demolition waste, car fluff, filters, plastic and rubber…) will be treated. The design point corresponds to an average heating value (HHV) of 13.1 MJ/kg (5600 Btu/Lb).
The first part of the paper addresses the engineering and construction phase of the project, which took 15 months in total. Key decisions and design options, including the choice and characteristics of a partially water-cooled grate, the use of the cooling water heat and the design features resulting in a low-NOx WtE plant, are discussed in detail.
The second part of the paper focuses on the construction and commissioning of the plant. Finally, the plant performance is documented. The main results are compared with the guaranteed values and the differences are discussed. The performance of the water-cooled grate is compared to that of other WtE plants.
Article written by Marcel Goemans, Patrick Clarysse, Joseph Joannès, Petra De Clercq, Silvia Lenaerts – Seghers Better Technology ; Karel Matthys, Kris Boels - IVAGO
Published in Chemosphere, Volume 50, Number 4, pp. 489-497, January 2003
ABSTRACT
The engineering, construction, performance and running costs of a catalytic flue gas cleaning component in the low dust area of a municipal waste incinerator is discussed. For this purpose, the case study of a Flemish incineration plant is presented, covering the history, the design procedure of the catalyst, relevant process data and the financial aspects.
A reliable PCDD/F-destruction by means of oxidation by the catalyst to typical values of 0,001 ng TEQ/Nm³ has been demonstrated. At the same time, NOx- and CO-emissions are reduced by 90% and 20% to about 50 mg/Nm³ and below 10 mg/Nm³, respectively.
2002
Article written by Daud Batchelor, Dirk Eeraerts, Patrick Smits - Seghers Better Technology
Published in Waste Management World, Issue September-October 2002
ABSTRACT
The pressing need to reduce greenhouse gas emissions places a considerable responsibility on those involved in the waste sector. Traditional methods of waste management such as landfilling are making a greater contribution to such emissions than alternatives such as waste-to-energy plants. Landfilling continues to be used, despite considerable developments in waste-to-energy technology in recent years.
This article assesses the relative impacts of both methods of waste management (landfill versus WtE) from a greenhouse perspective, taking Australia as an example.
Paper written by Marcel Goemans, Mark Périlleux – Seghers Better Technology
Presented at 12th European Conference and Technology Exhibition on Biomass for Energy, Industry and Climate Protection, Amsterdam (The Netherlands), 17-21 June 2002
ABSTRACT
The drive towards sustainable development provides new momentum to the use of biomass for energy production. In this paper, an overview of the variety of biomass streams and technologies for biomass utilisation for energy production is given to illustrate the wide range of options and choices to be made when developing a biomass-to-energy project.
Direct combustion of biomass on a water-cooled combustion grate or in a turbulent fluidised bed are used as examples to illustrate the importance of various parameters in the plant design to assure optimal use of biomass and maximal performance and availability of the biomass fired power plant.
Paper written by Mark Périlleux, Dirk Eeraerts - Seghers Better Technology
Presented at NAWTEC 10, Philadelphia (USA), 6-8 May 2002
ABSTRACT
The implementation of the European directive requiring a residence time of at least two seconds at a temperature above 850°C (1562°F), the change in waste characteristics, and the pursuit of higher thermal efficiencies has pushed many of the existing waste-to-energy (WtE) plants in Europe to their operational limits. Most existing WtE plants were not designed to operate under these conditions and may require modifications to the combustion system.
Within the Seghers Better Technology company, the Seghers BOILER PRISM was developed to deal with the cause of these problems, which are essentially related to insufficient mixing and burnout of the flue gases in the combustion area. By passing the BOILER PRISM, the flue gas flow is divided into two parallel flows prior to entering the first radiant pass of the boiler. This division is achieved by means of a prism shaped construction, which is water-cooled and integrated with the natural circulation system of the boiler.
Additional secondary air injection nozzles are fitted in the prism. This technology results in a more uniform flue gas temperature and a complete combustion of the flue gas immediately above the prism. In the Bonn plant, these improvements in the combustion process resulted in a decrease of the fireside cleaning requirements of more than 50%.
Paper written by Daud Batchelor, Dirk Eeraerts, Silvia Lenaerts - Seghers Better Technology
Presented at ENVIRO 2002, Melbourne (Australia), 7-12 April 2002
ABSTRACT
Forward-looking countries have adopted a battery of strategies across a wide range of fields, including waste management, targeted to reduce greenhouse gas (GHG) emissions, in line with their support for the Kyoto Protocol. GHG emissions from the waste sector are predominantly methane, generated from the anaerobic decomposition of organic matter in landfills.
In continental Europe where the movement for better environmental practices and technologies has generally preceded others, there has been a strong movement away from landfilling as a final disposal option, towards other approaches, especially incineration with energy recovery. In other countries, notably Australia, Britain and the United States, where there is still strong public antipathy to incineration, the debate continues on whether residual waste from the recycling of municipal solid waste should be landfilled or incinerated.
Given the urgency for measures to address the global warming problem effectively, this paper examines the latest data and published studies to identify which of the cited technologies is better in terms of reducing GHG emissions. Estimates are developed over the period of the respective life cycles to ensure validity of the comparisons made.
Based on established factors, the magnitude of GHG reduction will be quantified, and discussed in terms of the national reduction targets for Australia and the United States under the terms of the Kyoto Protocol.
Other environmental and economic aspects of the technologies discussed will be briefly considered to identify important trends that are relevant in making decisions on their application.
Paper written by Mark Périlleux, Glenn Creten – Seghers Better Technology ; Joachim Kümmel – IBB Engineering
Presented at INFUB - 6th European Conference on Industrial Furnaces and Boilers, Lisbon, (Portugal), 2-5 April 2002
ABSTRACT
The patented SEGHERS-IBB Prism technology constitutes a novel and innovative means of increasing combustion and boiler performance, based on the introduction of a prism-shaped body in the first empty boiler pass. The prism allows a highly optimised secondary air injection and combustion control strategy leading to quasi uniform flue gas conditions at a very early stage and virtually independent of the heat release profile on the grate. This not only leads to increased performance in new boilers, but also helps to solve the severe corrosion problems in the radiant and superheater sections that many existing plants are dealing with.
The design, engineering and performance of the patented BOILER PRISM technology, both in new and existing plants is studied and illustrated by means of three case studies.
A first case deals with the extensive experience obtained from the three incinerator lines of the Bonn plant (Germany) that were equipped with a BOILER PRISM in 1997-1999. Operation results after 4 years will be presented and discussed.
The retrofit of the secondary air injection system with BOILER PRISM in an existing WtE plant in The Netherlands (AZN, 600.000 TPA) is discussed as second case. The installation is started up and commissioning tests on one line of the plant are going on for the moment. The results from these tests will be compared to the CFD-simulations and engineering calculations performed during the design of the project, as well as to flue gas measurements prior to the retrofit, allowing a detailed assessment of the performance of the prism.
The last case discusses the engineering of a new incineration plant in Germany (MKE Mannheim, 200.000 TPA). Extensive use is made of CFD-simulations to optimise the location and geometry of the BOILER PRISM, as well as the secondary air injection system.
Paper written by Michel Distelmans - Seghers Better Technology
Presented at R'02 6th World Congress on Integrated Resource Management, Geneva (Italy), 12-15 February 2002
ABSTRACT
In this paper a method of pretreatment of municipal solid waste is presented which allows for a simple and reliable resource recovery as well as an improvement of the different final treatment methods.The presented technology is the Seghers’ waste pretreatment based on the DANO DRUM. Solid wastes are fed directly to the system, which mixes and homogenizes the waste. Because of the selective attrition inside the drum, mainly putrescibles and paper report to a smaller size fraction. At the end of the drum, an integrated screen produces 3 waste fractions: an undersize fraction containing mostly organic materials, a middle size fraction with a higher heating value containing most of the metals and a larger size fraction.
In the paper an increase in yield and quality from biological treatment is shown, as well as ferrous and nonferrous metals recovery, and a cost reduction with regard to thermal recovery of the remaining fraction. The simple petreatment system produces significant waste derivation from landfill and recovery rates.
The flexible waste pretreatment allows for changes of waste management policy due to evolutions in final treatment technologies, degrees of public acceptance and secondary resource market fluctuations. The paper shows how the DANO DRUM pretreatment can be optimised for the different final waste treatment methods by a tuning of the present process, without major investments.
Paper written by Mark Périlleux – Seghers Better Technology
Presented at Waste-to-Energy 2002 Conference, Brussels (Belgium), 21-23 January 2002
INTRODUCTION
Thermal valorisation of municipal solid waste is a very complex process. Energy-from-waste (EFW) plants are today still the subject of many discussions and hold on low esteem by the public. However conventional modern stoker-fired incineration plants, based on proven technology, are still recognised as the most economical, reliable and environmentally sound solution for waste treatment, in full compliance with the most stringent emission standards. This is possible when basic design criteria are taken into consideration when building EFW plants.
A large number of the existing waste incineration plants however were not designed to comply with these design criteria. The consequences of this disregard became apparent in several incineration plants:
- Large scale corrosion on the membrane walls in the first two radiant passes of the boiler
- High-temperature corrosion on the superheater surfaces
- Reduced plant availability or short operation periods between manual cleaning as result of heavy slagging and ash deposits on the boiler heating surfaces.
The most effective measure against these observed problems, despite of the extremely heterogeneous characteristics of residual waste as fuel, is to improve and optimise the combustion process not only on the grate system but also in the first pass of the integrated boiler. The effect of the implemented measures should result in a complete burnout with a uniformly distributed flue gas flow, at a temperature of approx. 1000°C at the entrance of the first radiant pass of the boiler. This paper describes and illustrates in detail how the Seghers-IBB PRISM can assist in this process.
2001
Paper written by Daud Batchelor, Dirk Eeraerts, Herman Sioen - Seghers Better Technology
Presented at WASTE MANAGEMENT 2001 Conference, Kuala Lumpur (Malaysia), 6-9 November 2001
ABSTRACT
A sustainable development approach requires that the concept of “waste” is replaced by an emphasis on waste as a “resource” and on the “conservation of energy and materials”.
Sustainable waste management requires good Integrated Waste Management Systems and government policies that encourage waste prevention, reuse, and both materials and thermal recycling as valid options. Life Cycle Analyses (LCA), augmented by economic analyses, are extensively used to choose between alternative waste management strategies. Life Cycle Analysis is a better decision support tool than the waste management hierarchy for determining the most sustainable solutions. The successful outcome of sustainable waste management policies and practices in the more progressive countries of West Europe, together with the use of proven technologies, indicate useful directions to guide others in the path to sustainable waste management.
Experience shows that Waste-to-Energy (WtE) plants with advanced flue gas cleaning have an important role to play in municipal solid waste treatment. Clearly, there is no conflict between having high materials recycling rates with at the same time extensive thermal recycling through WtE plants. WtE technologies bring about a major reduction in volume and reactivity of municipal solid waste, substitute for fossil fuels in energy generation, and facilitate sizeable greenhouse gas abatement. WtE plants have a special role to play in countries where land is scarce, and those with wet tropical climates where high leachate volumes are generated from landfills.
Paper written by Michel Distelmans, Simon Martin - Seghers Better Technology
Presented at Sixth International Conference on Engineering for Profit from Waste, London (UK), 13-14 November 2001
ABSTRACT
Materials recovery and recycling are high on the priority list of waste management strategies, very often higher than mass incineration or landfilling, which can meet public resistance. In this paper a method of pre-treatment of the waste is presented which allows for a simple and reliable resource recovery as well as an improvement of the different final treatment methods.
The presented technology is the Seghers waste pre-treatment based on the DANO DRUM. Solid wastes are fed directly to the system, which mixes and homogenizes the waste. Because of the selective attrition inside the drum, mainly putrescibles and paper report to a smaller size fraction. At the end of the drum, an integrated screen produces three waste fractions: an undersize containing mostly organic materials, a middle size fraction with a higher heating value containing most of the metals and a larger size fraction.
In the paper an increase in yield and quality from biological treatment is shown, as well as ferrous and non-ferrous metals recovery, and a cost reduction with regard to thermal recovery of the remaining fraction. The simple pre-treatment system produces significant waste deviations to landfill and high recovery rates.
The flexible waste pre-treatment allows for changes of waste management policy due to evolutions in final treatment technologies, degrees of public acceptance and secondary resource market fluctuations. The paper shows how the pre-treatment can be optimised for the different final waste treatment methods by a tuning of the present process, without major investments.
Paper written by Marcel Goemans and Mark Périlleux - Seghers Better Technology
Presented at Water and Waste Global Summit, Singapore, 12-14 September 2001
ABSTRACT
The drive towards sustainable development provides new momentum to the use of biomass for energy production. In this paper, an overview of the variety of biomass streams and technologies for biomass utilisation for energy production is given to illustrate the wide range of options and choices to be made when developing a biomass-to-energy project.
Direct combustion of biomass on a water-cooled combustion grate or in a turbulent fluidised bed are used as examples to illustrate the importance of various parameters in the plant design to assure optimal use of biomass and maximal performance and availability of the biomass fired power plant.
Article written by Bart Adams - Seghers Better Technology
Published in Kluwer Nieuwsbrief Milieutechnologie, Editie September 2001
ABSTRACT
Tijdens de verbranding van afvalstoffen worden alle dioxines die aanwezig zijn in het afval volledig afgebroken. Bij het afkoelen van de verbrandingsgassen worden er echter opnieuw dioxines gevormd. Experimenteel stelde men vast dat dit voornamelijk geschiedt in het temperatuursbereik van 450-250°C en in aanwezigheid van stofdeeltjes. Naast de jaarlijkse onafhankelijke controlemeting, eist de Vlaamse milieuwetgeving tevens dat alle huisvuilverbrandingsinstallaties sinds 1 januari 2000 uitgerust zijn met een continue bemonstering voor dioxines.
De reiniging van de rookgassen die ontstaan bij een verbrandingsproces gebeurt door een combinatie van primaire en secundaire maatregelen. Primaire maatregelen zijn gericht op het vermijden van de vorming van polluenten. Secundaire maatregelen hebben als doel de verwijdering of vernietiging van de aanwezige polluenten.
Het artikel bespreekt een aantal gekende technieken en recente ontwikkelingen in Vlaanderen inzake dioxine-emissiereductie.
Paper written by Bart Adams, Marcel Goemans, Joseph Joannès - Seghers Better Technology
Presented at Incineration 2001 - 3rd International Symposium on Incineration and Flue Gas Treatment Technologies, Brussels (Belgium), 2-4 July 2001
ABSTRACT
Immediately after the start-up of the recently refurbished municipal solid waste incineration (MSWI) plant of ISVAG (Wilrijk, Belgium), an extensive dioxin monitoring campaign was initiated. Numerous continuous and discontinuous stack measurements, as well as simultaneous measurements at different locations were performed during normal operation and operation on natural gas. Data-analyses indicated clearly that nearly the entire dioxin emission could be attributed to the memory effect situated in the two-stage wet scrubbers of the plant.
Inspection of the fingerprints showed that the difference between both incinerator lines was most significant for low chlorinated congeners. This explains the considerable difference in toxicity of the emissions for virtually identical raw gas concentrations for both lines. The decrease in dioxin release on both lines was shown to be proportional to approximately (time)-1.
Finally, the data demonstrated chlorination/dechlorination phenomena of PCDD/F in the wet scrubber. An approximate dioxin mass balance for the plant (in absence of the memory effect) was established and toxicity values according to the I-TEQ and WHO-TEQ system were compared.
Article written by Bart Adams, Marcel Goemans, Silvia Lenaerts - Seghers Better Technology
Published in Het Ingenieursblad (KVIV), June 2001
ABSTRACT
Geen enkele industriële sector kwam het afgelopen decennium zo vaak aan bod en lag zo intens onder vuur in de media en de politiek als de afvalverbranding. Getuigen hiervan zijn de tientallen boeken, studies en artikels die aan dit onderwerp werden gewijd.
Na een periode waarin de wetgeving inzake rookgasemissies drastisch verscherpte en de sector reageerde met de versnelde verbetering van bestaande en de ontwikkeling van nieuwe reinigingstechnologieën, is het tijd om een stand van zaken op te maken. Een overzicht van de huidige technieken toont aan dat de hedendaagse verbrandingsovens complexe chemische fabrieken bevatten die hen in staat stellen de rookgassen verregaand te reinigen en het impact op het milieu tot een minimum te reduceren. Toekomstige technologieën beogen een verdere reductie van de hoeveelheid geproduceerde residu’s, een nog grotere bedrijfszekerheid en het opdrijven van de energetische efficiëntie.
Inventarisatie van de huidige huishoudelijke afvalstromen en analyse van de te verwachten evoluties tonen aan dat, zelfs bij het verder uitwerken van de selectieve ophaling en gedeeltelijke recyclage, de hoeveelheid te verwerken restfractie in Vlaanderen in de nabije toekomst in het beste geval zal stagneren. Tevens blijkt uit een recente studie van de Vito dat moderne afvalkrachtcentrales, op voorwaarde dat ze uitgerust worden met een geavanceerde rookgasreiniging, tot de beste keuze behoren voor de verwerking van het restafval en dat zij daarenboven het enige alternatief zijn waarvan over langere termijn de betrouwbaarheid en performantie werd aangetoond.
Een overzicht van de beschikbare technologieën illustreert de grote verscheidenheid en complexiteit van de hedendaagse rookgasreinigingsinstallaties. De stand der techniek laat toe door de combinatie van gepaste componenten bedrijfszekere installaties te ontwerpen en te bouwen. Nu reeds dienen deze rookgasreinigingsinstallaties onder alle omstandigheden aan de (toekomstige) milieunormen te voldoen.
Het samenvoegen van verschillende rookgasreinigingscomponenten, het streven naar de integratie van de rookgasreiniging met de overige onderdelen van de afvalverbrandingsinstallatie en de groeiende aandacht voor de verwerking van de vaste residu’s vormen de belangrijkste toekomstige trends inzake rookgasreiniging.
Paper written by Marcel Goemans, Patrick Clarysse, Joseph Joannès, Petra De Clercq - Seghers Better Technology ; Karel Matthys, Kris Boels – IVAGO Ghent
Presented at PowerGen, Brussels (Belgium), 29-31 May 2001
ABSTRACT
The IVAGO waste incineration plant (Ghent, Belgium) consists of two incinerator lines, each consisting of a Seghers MULTI STAGE GRATE, cooling tower, semi-wet reactor, adsorbent injection, baghouse filter, and one-stage wet scrubber. Within the next two years, the cooling towers will be replaced by waste heat recovery boilers (40 bar, 400°C) to upgrade the incinerator to an Energy-from-Waste plant. The plant has a total capacity of 100.000 tonnes per year.
To meet future European emission limits, IVAGO decided in the summer of 1999 to retrofit the existing incinerator with a SEGHERSdeDInOX installation. The paper illustrates that the deDInOX concept is an efficient way to reduce both NOx and PCDD/F emissions in one installation. PCDD/F emissions reduction is accomplished at a minimal supplemental cost.
At the Ghent MSWI plant, the NOx emissions are reduced by more than 90% to 30-50 mg/Nm³. In addition, dioxins and furanes are destroyed by a factor 100 to less than 1% of the norm of 0.1 ng TEQ/Nm³. Ammonia slip is typically below the detection limit of 2 mg/Nm³. All values are given at dry, 11% oxygen conditions. CO reduction is about 20%.
Paper written by Marcel Goemans, Patrick Clarysse, Joseph Joannès, Petra De Clercq - Seghers Better Technology ; Karel Matthys, Kris Boels – IVAGO Ghent
Presented at International Conference on Industrial Atmospheric Pollution: NOx emission control, Paris (France), 21-22 March 2001
ABSTRACT
See: PowerGen, Brussels (Belgium), 29-31 May 2001
2000
Paper written by Bart Adams, Marcel Goemans, Joseph Joannès – Seghers Better Technology
Presented at ISWA International Symposium on Waste Management in Asian Cities, Hong Kong (China), 23-26 October 2000
ABSTRACT
An extensive dioxin monitoring campaign was conducted during the start-up of the refurbished Energy-from-Waste plant of ISVAG (Wilrijk, Belgium). Frequent stack-emission measurements, combined with simultaneous measurements at different locations in the Air Pollution Control system, and fingerprint analyses clearly showed that virtually the entire dioxin release is caused by the memory-effect situated in the wet scrubbers. Furthermore, it was shown that this dioxin release decreases on both lines in proportion to approximately (time)-1. In addition, the data demonstrated chlorination/dechlorination phenomena of PCDD/F in the wet scrubber, and the large effect on the emissions (expressed in TEQ) of small differences in the degree of chlorination of the released dioxins.
Paper written by Bart Adams, Joseph Joannès - Seghers Better Technology ; Alfons Buekens - Vrije Universiteit Brussel ; Walter Ex - ISVAG Wilrijk
Presented at DIOXIN 2000, Monterey, California (USA), 13-17 August 2000
ABSTRACT
During the start-up of the recently refurbished municipal solid waste incineration (MSWI) plant of ISVAG (Wilrijk, Belgium), an extensive campaign was launched to monitor the emission of dioxins. The resulting data indicate that virtually all current dioxin release is due to memory effects situated in the wet scrubber, which was unaffected by the refurbishment and located after a new semi-dry scrubber with baghouse filter.
The data obtained provides valuable information leading to a better understanding of this memory effect.
Paper written by Marcel Goemans, Olivier Pollet, Quentin Olivier – Seghers Better Technology
Presented at First World Conference and Exhibition on Biomass for Energy and Industry, Sevilla (Spain), 5-9 June 2000
ABSTRACT
The potential of steam production from co-combustion of industrial WWTP-sludge and five by-products of a chemical industry was evaluated in a semi-industrial atmospheric fluidised bed furnace. The chemical by-products had high concentrations of cobalt (Co) and manganese (Mn). Recovery of Co and Mn was desired.
An efficient, complete and autothermal combustion was achieved under all conditions and waste compositions. The process steam generated from co-combustion will cover about 5-10% of the total steam consumption of the chemical production plant. Nickel (Ni), Co, and Mn were recovered in the fly ashes with an efficiency of up to 90%. The concentration and chemical composition of the fly ashes allow recovery of Co and Mn.
The full-scale unit (10 MWth) is currently in the design and construction phase, and will consist of a feed preparation and mixing installation, a bubbling fluidised bed furnace with integrated steam boiler (43 bara, saturated), a two-stage, dry sorbent injection, a ceramic high-temperature filter for acid and dust removal and metal recovery, and a catalytic reactor for oxidation of dioxins and furans and reduction of NOx.
Paper written by Marcel Goemans, Bart Adams, Quentin Olivier, Olivier Pollet – Seghers Better Technology
Presented at IT3 - International Conference on Incineration and Thermal Treatment Technologies, Portland, Oregan (USA), 8-12 May 2000
ABSTRACT
See First World Conference and Exhibition on Biomass for Energy and Industry, Sevilla (Spain), 5-9 June 2000
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