VATIS Update Waste Management . Jul-Aug 2004

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Waste Management Jul-Aug 2004

ISSN: 0971-5665

VATIS Update Waste Management is published 4 times a year to keep the readers up to date of most of the relevant and latest technological developments and events in the field of Waste Management. The Update is tailored to policy-makers, industries and technology transfer intermediaries.

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UNEP for global clean-up of PCBs

Polychlorinated biphenyls or PCBs are a section of synthetic organic chemicals that are among the most widespread of all global environmental pollutants. They are present in air, water, soil, food and the fatty tissues of humans and animals. Mr. Klaus Toepfer, Executive Director of the United Nations Environment Programme (UNEP) states that The financial and technical challenges of eliminating PCBs from the planet will require a vigorous partnership between public and private sectors.

In the past, the low inflammability of PCBs led to their extensive application in electrical equipment such as transformers and large capacitors utilized in power lines and major facilities. They have also been used as additives in paint, carbonless copy paper and plastics. Although production is now banned under the Stockholm Convention on Persistent Organic Pollutants, PCBs continue to pose a risk to human health and the environment because of the wide array of PCB-containing electrical equipment presently in use. Large amounts of wastes containing PCBs or contaminated by PCBs are being held at temporary storage locations, particularly in developing nations. In addition, large amounts of PCBs have already been discharged into soils, rivers and lakes over the years. Further releases continue to result from repair and decommissioning of equipment, accidents, demolition of buildings and continued existence of imperfectly sealed landfills and waste drums.

The Stockholm Convention has set the year 2025 as the deadline for governments to phase out in-place equipment comprising PCBs, as long as the equipment is maintained in a way that prevents leakage. It also grants another three years to ensure eco-friendly management of PCB-tainted wastes. At a meeting in Switzerland between 9-10 June, sponsored by UNEP and financed by the Government of Switzerland, donors and commercial firms from around the globe came together to promote international efforts aimed at eliminating PCBs. The meeting provided donor agencies and PCB-related industries the opportunity to discuss upcoming needs for PCB management and disposal, the international policy framework, logistical issues and available capacities for PCB storage, management, transportation and disposal.

Contact: Mr. Michael Williams, UNEP, Geneva, Switzerland.



Eliminating POPs from the Philippines

On 27 February 2004 the Philippines became a party to the Stockholm Convention on Persistent Organic Pollutants (POPs), which came into effect on 27 May 2004. Ms. Elisea G. Gozun, Secretary to the Department of Environment and Natural Resources (DENR), urged concerned agencies and various organizations to bolster efforts aimed at eliminating POPs in the country. Recently, a chemical control order for PCBs, the DENR Administrative Order 2004-01, was issued to provide guidelines for the proper use, disposal and storage of PCBs, including clean-up activities of PCB-contaminated sites.

DENR, through the Environmental Management Bureau (EMB), is devising a concrete plan to completely phase out PCBs, one of the POPs identified by the convention. Earlier this year, DENR-EMB had endorsed a project for funding to the Global Environmental Facility, through the United Nations Industrial Development Organization and the United Nations Development Programme. This will allow establishment of a facility for destroying wastes and stockpiles of POPs.


Samsung to eliminate hazardous chemicals

Samsung, a  consumer electronics company based in the Republic of Korea, has decided to phase out the use of hazardous chemicals in its products. Tests performed by Greenpeace on a wide range of consumer goods, which included a Samsung mobile phone and TV, revealed that most products contained phthalates, synthetic musks, brominated flame retardants, alkylphenols or organotin compounds. Discussions initiated by Greenpeace with regard to the companys use of brominated flame retardants and phthalates resulted in Samsung committing itself to adopt cleaner alternatives within a fixed time-frame. This pledge upgrades Samsungs ranking on the Greenpeace products database from red to orange, making Samsung the first producer to have its rating upgraded since the start of the campaign.


China takes steps to ratify POPs treaty

As a prelude to China signing the Stockholm Convention on POPs, which is aimed at controlling toxic pollutants, an application for the ratification has been submitted to the National Peoples Congress, the nations top legislature. POPs are highly toxic chemical substances that can cause irreparable damage to humans and the environment. Mr. Wang Jirong, Vice-minister of the State Environmental Protection Administration (SEPA), stated that China is already working on a plan to implement the convention as well as towards developing alternatives to POPs. The new measures will include achieving safe treatment of hazardous chemical waste, setting up a national chemical and pesticide management system and seeking additional international financial and technical support.


Solid waste treatment plant in Viet Nam

Lemna International Group, based in the United States, is scheduled to build a US$36 million treatment plant for the disposal of urban solid wastes in Viet Nams Ho Chi Minh City. Under an agreement with the citys Natural Resource and Environment Department, Lemna would be responsible for the design, construction, installation and operation of the facility by applying advanced technology. Built over an area of 70 ha, the 1,200 t/d plant is scheduled to feature purpose-built units to convert wastes into organic fertilizer. The plant will be turned over to the city after 30 years of operation.

Viet Nam Infoterra, Newsletter, 1/2004

Korean proposal aims to dispose of industrial wastes

Plans have been announced in the Republic of Korea to embark on a major clean-up operation of industrial wastes, construction material and dilapidated mines that are damaging the environment. The Korean government has committed itself to clean up 29 old mines across the nation by 2007. These steps were included in a comprehensive anti-waste project set out jointly by the Ministry of Environment, Ministry of Construction and Transportation and the Korea Forest Service to dispose of huge amounts of neglected waste. According to the plan, 810,000 t of industrial refuse remaining in 45 workplaces nationwide will be eliminated by 2005, while waste treatment facilities will be built near 29 mines to prevent pollutants filtering to surrounding areas.


Permit for dealers in hazardous wastes

In China, a State Council ordinance, which entered into force on 1 July 2004, has made it compulsory for businesses engaged in collection, storage and disposal of hazardous wastes to obtain a licence from the government before starting operation. Companies already engaged in this business have to apply for permits 30 days prior to the expiration date of their existing authorization documents. Methods on the Management of Hazardous Wastes Process Permits, which has been approved by Premier Wen Jiabao, comprises 33 articles in 6 chapters, which provide for qualifications for dealers, application procedure for permit, supervision mechanism and the legal consequences of possible violations.


The Philippines to reduce PCB imports

The 2004-01 Administrative Order promulgated by the Department of Environment and Natural Resources (DENR) in the Philippines will reduce and eliminate importation and use of hazardous chemicals. Under this directive, owners or operators, as well as suppliers handling PCBs, must register within three months with the Environmental Management Bureau after the effective date of the chemical control order. Among the PCBs-related items that must be clearly marked are transformers and capacitors using PCBs, electric motors, hydraulic equipment, heat transfer systems and PCBs packaging that are stored for treatment and disposal. Storage facilities must be marked clearly by putting fences, posts or walls. Industries have to undertake self-inspection at 30 day intervals.


Management of toxic wastes in China

Hazardous wastes being generated in China on a yearly basis includes 10 million tonnes of industrial waste, 650,000 t of biomedical waste and 115,300 t of radioactive waste. However, only 24.2 per cent of these are disposed of while about one-third are stored in makeshifts. The availability of only six complexes for the proper disposal of waste has led to a sizeable portion of waste being either buried or burned untreated by unauthorized small trash businesses.

According to Mr. Pan Yue, Vice-director of the State Environmental Protection Administration (SEPA), four major problems plaguing the hazardous waste treatment industry are inadequate disposal complexes, outdated technologies, no liability-compensation system and absence of a unified monitoring system and emergency mechanism. SEPA is scheduled to enact a regulation for licensing businesses pertaining to hazardous waste treatment. The new legislation will raise standards to enter into the hazardous waste treatment industry, while classifying licenses into two categories one permits only collection while the other also allows for storage and disposal. In addition, it will define supervision powers of both SEPA and the public.



Recent trends in recycling of plastic waste

The plastics recycling industry has grown enormously because of the exponential increase in plastic waste, its recycling potential and the low cost of recycling. Some notable achievements from around the globe are mentioned below.
  • Advanced Recycling Technology, Belgium, has developed an extruder to blend a wide range of plastic materials such as PVC, PET and PS. The mixture can then be formed into stable moulded products, which can even have properties similar to or better than wood.
  • Alberta Plastics Recycling Association has evolved technology for advanced recycling of some plastics to supplement existing mechanical recycling processes such that the products after purification are identical to present feedstocks and monomers used to manufacture new products.
  • National Renewable Energy Laboratory (NREL), the United States, has developed a process based on the pyrolysis (heating in the absence of oxygen) of certain waste streams. This process retrieves monomers, basic building blocks of a polymer, and high-value chemicals used to make new plastics. A major benefit of this method is that waste plastics do not require to be separated early, thereby eliminating a labour-intensive step in conventional processes. Monomers and high value chemicals, reclaimed from manufacturing or post-consumer wastes through sequential pyrolysis, undergo detailed chemical analysis. This helps determine the conditions that allow control of pyrolysis reactions, permitting the designing of a process to collect the desired products in high yields and reduce the requirements for subsequent separation and purification of the target product.
  • NREL has demonstrated isolation of caprolactam with yields of 85 per cent from waste carpets.
  • Researchers in the United States have developed technology for separating individual plastics of high purity from waste streams containing a mixture of plastics. This technology has been used to separate acrylonitrile-butadiene styrene (ABS), high-impact polystyrene (HIPS) and PP from other plastics without using hazardous chemicals during scrap shredding and metal recovery operations.
  • In India, the Indian Centre for Plastics in Environment (ICPE) has developed a compactor for recycling waste plastics. PET bottles, cups, trays, etc. are reduced to one-tenth their volume and formed into plastic bricks, which can be transported to recycling facilities at affordable freight costs. Moreover, new technologies examined by ICPE include skin plastic, injection moulding to accept corrugated waste so as to prevent the wastes of paper, wood and metals from getting into the recycling loop containing only the rich plastic waste.
  • A researcher at S.P. Chowgule College, India, has developed a low-cost process to recycle waste plastic milk sachets using cheap additives. This technology has a very low energy requirement and is reported as environmentally benign.


Moulding process facilitates recycling

Researchers with the Department of Materials Science and Engineering at the Massachusetts Institute of Technology in the United States have developed a process to mould plastics at room temperature. The new procedure involves squeezing certain combinations of polymers together, causing them to interact such that they assume a mouldable liquid-like state. This method yields materials called baroplastics, which can be made from the same material as conventional plastics. A notable benefit is that baroplastics can be recycled many times without compromising its quality, unlike plastics recycled by traditional methods.


New technology for plastics segregation

TLT Turbo Lamiare Trenntechnik of Germany offers patented technology for segregating plastics. In the new method, pre-purified flake is mixed in a suspension cylinder with water or any another fluid with a defined density. The solid-fluid suspension is then pumped into a separation cylinder where the patented process transforms the turbulent flow into a constant laminar flow. Various components of the material separate in different zones of the separation cylinder according to their specific gravity in relation to the density of the separation medium. The lighter fractions are vented at the top while heavier constituents are discharged at the bottom. A screen drainage is used to separate the plastics and fluid, and the fluid is re-pumped into the suspension cylinder.

The plant design can be extended to include further separation units using other separation media like brine or ethanol. Salient features of the TLT process include:
  • Excellent separation of plastics of different density (>0.03 m/cm3);
  • Fine separation independent of the size or form of the flake;
  • Continuous bar capacity and material take-off;
  • High throughput owing to quick separation;
  • Good economics;
  • Reliable operation due to simple technology with robust aggregates and slowly rotating parts;
  • Compatibility with all automatic control systems;
  • Low energy consumption;
  • Low ground noise; and
  • Trouble-free integration into all plastic recycling systems.

The TLT plastics separator, which is 6 m high and needs a floor space of 15 m2, has a throughput of over 1 t/h.

Contact: TLT Turbo Lamiare Trenntechnik, Frankfurt, Germany. Tel: +49 (69) 6773 0646




Plasma technology to recover plastics

In Japan, Kumamoto University and Matsushita Electric Industrial Co. Ltd. have developed the worlds first technology to recover both metals and plastics from plastic products laminated with metal films. Metal and plastic components are separated physically by applying shock waves for an extremely short period (20 s). Virtually unaltered plastic is obtained, which can be recycled to manufacture new products. This technology focuses on two important features, namely:
  • Applicable on a variety of metals and plastics, since shock wave and heat, as seen with lightning, are produced with plasma discharge, while this technology can control electrical conditions for discharging; and
  • Metal fraction can be recovered efficiently and cheaply, with the least possible impact on the environment, since delamination is carried out by a method using an instantaneous electric charge rather than a large amount of chemicals.

The new process can be used to recycle plastic used in the casings of home appliances, electric circuit boards, automobiles, recreational facilities, etc.

Contact: Mr. Akira Kadota/Mr. Wilson Solano, Japan. Tel: +81 (3) 3578 1237; Fax: +81 (3) 5472 7608.


Purification of mixed plastic wastes

In Canada, a research team at the University of Western Ontario, has developed technology to separate mixed waste plastics based on the difference in electrostatic charges. It is known that polymers attain a positive/negative charge in relation to each other, depending on the material they contact. The polarity of the charge that develops between polymers can be easily summarized in what is known as a triboelectric series. In contact, a polymer higher in the series will charge negatively in relation to any polymer lower in the series.

The separation process involves reducing plastic wastes into 1/4 inch pieces, washing and drying to remove contaminants and then passing the shredded material through a charging drum. Once charged, the material is allowed to fall through a high voltage electrical field. The plastic material, depending on the amount and polarity of the induced triboelectric charge, gets deflected within the electric field into appropriate separation bins. Benefits offered by this pollution-free process are:
  • Mixtures of two or more polymers can be separated into pure streams;
  • Highly efficient;
  • No chemicals or elaborate pretreatment needed;
  • Requires little energy;
  • The end products can be used to replace virgin materials; and
  • Several mixtures have achieved purity levels exceeding 99 per cent.

Contact: Mr. John Small, Industry Liaison Officer, Western Ontario University, Canada. Tel: +1 (519) 6612 111, ext. 84516; Fax: +1 (519) 6613 907



Recycling industrial plastic scrap

Itec Environmental Group, the United States, is offering ECO2 system for recycling post-consumer as well as industrial plastic wastes. This system uses carbon dioxide (CO2) to clean plastics and separate glue, labels, oil and other contaminates from the plastic. Machinery used in the ECO2 system is designed, developed and produced by Cool Clean. Itec has entered into agreements with Cool Clean to manufacture the CO2 cleaning equipment exclusively for the ECO2 system.

Each Generation-2 ECO2 system completes two cycles per hour and can produce over 454 kg/h of clean, recyclable plastic, plus several litres of residual oil. Tests have exhibited that ECO2 system can successfully process six types of post-consumer contaminated plastics, including:
  • Pesticide containers;
  • Mixed colour HDPE containers;
  • Natural post-consumer HDPE containers;
  • Oil contaminated plastics;
  • Post-consumer PET; and
  • Paint buckets.

Contact: Itec Environmental Group, 132, South 3rd Avenue, Oakdale, California 95361, United States of America.
Tel: +1 (209) 8483 900.


Plastic recycling

Luxus Ltd., the United Kingdom, is offering various processes to recycle plastics. Plastic scrap is segregated into different polymer types, metal parts and labels are removed along with excess dirt and dust. Cleaned waste is shredded and granulated. After granulation, a sample of the reground material is tested to find out the particular grade of thermoplastic compound the material is best suited for.
Blending is the process of mixing multiple batches of a single polymer type to create a homogenous mix of product, thus ensuring consistency throughout the resulting batch of material. As the material is fed into the blender, a vertical rotating screw continually augers it to the top of the blender and then sprays it from the top of the screw. Foils set on the inside of the blender then help to further disperse and combine the material. This procedure continues until a uniform blend of product is achieved.

The compounding process is similar to that employed in injection moulding machines, where plastic and additives are metered into a hopper at one end of a barrel. The material is transported along the length of the barrel via an Archimedes screw, and gets melted on the way on being heated using external heater bands and through heat caused by friction. Specially designed sections of the screw knead, mix and compound the plastic, additives and fillers. At the end of the barrel, melted plastic flows through a wire screen which filters out any residual dirt, grit or other contaminants and is then forced through a die plate. Plastic exiting the die is cut into pellets, cooled by quenching in water and dried as it is blown around the pipework and into packaging at the end of the line.

Contact: Luxus Limited, Belvoir Way, Fairfield Industrial
Estate, Louth, Lincolnshire LN11 0LQ, United Kingdom.
Tel: +44 (1507) 604 941; Fax: +44 (1507) 609 154.


Reclaiming materials from scrap vehicles

In the United States, a Cooperative Research and Development Agreement (CRADA) has resulted in the development of a recycling process for reclaiming more usable materials from end-of-life vehicles (ELVs). The CRADA was evolved by the Department of Energy between American Plastics Council, Argonne National Laboratory and USCARs Vehicle Recycling Partnership (Daimler-
Chrysler Corp., Ford Motor Corp. and General Motors Corp.).

At present, around 75 per cent of materials from ELVs are recycled. After the removal of usable parts, for resale or re-manufacturing, the leftover hulk is shredded to separate ferrous and non-ferrous metals, both of which are recycled. Non-metallic scrap or shredder residue comprises a mixture of polyurethane foams, polymers, a fines fraction which includes metal oxides, glass and dirt and small amounts of ferrous and non-ferrous metals. For each tonne of metal fraction reclaimed by a shredding facility, roughly 227 kg of shredder residue is produced. The two-stage process at Argonnes pilot facility begins with bulk separation of all shredder residue into the below mentioned categories:
  • Fines (iron oxides, other oxides, glass and dirt);
  • Polyurethane foam;
  • Polymers (polypropylene, ABS, polyethylene, nylon, PVC, polyester, etc.); and
  • Ferrous and non-ferrous metals.

The pilot facility also incorporates a plastics separation function to recover major plastics from shredder residue.

Contact: Mr. E. J. Daniels, Argonne National Laboratory, United States of America. Tel: +1 (630) 2525 279



Closed-loop process for recycling nylon

DuPont Engineering Polymers, the United States, is offering closed-loop nylon recycling process to convert parts made of glass- or mineral-filled Nylon 6 or 66 into first-use quality material. The economically viable and environment-friendly Composite Recycle technology dissolves used polyamide and removes contaminants and fillers. Molecular weight of the recovered polyamide is raised to the level needed for the final application. Resin that is essentially equivalent to virgin nylon is generated.

DuPont and DENSO announced a joint development programme to test the viability of this technology by converting used radiator end tanks into new models. The outcome from material and in-use component tests by DENSO indicate that this technology is one of the most effective methods for raising the recycle ratio of end-of-life vehicles in the future.



On-site disposal of infectious wastes

In the United States, WPS Co. is offering patented technology to convert infectious medical wastes into a safe, confetti-like material, which can be disposed of as ordinary trash. Referred to as the Steam Sterilizer Macerator (SSM), red bag wastes are processed using superheated water while simultaneously macerating the solids. The resultant material complies with OSHA standards for ordinary disposal because it is non-infectious, non-hazardous as well as unrecognizable.

Designed for use on-site at hospitals and nursing homes, SSM reduces the volume of solid wastes by 80 per cent, lowers hauling costs and eliminates transport and handling liabilities. WPS recently supplied a system to Johns Hopkins University School of Medicine for beta testing.

Contact: WPS Co., United States of America. Tel: +1 (410) 5244 245.


Automated waste handling system

A new automated vacuum transport system developed by Envac Scandinavia AB, Sweden, will be installed at St. Olav University hospital in Norway. Reported to be the worlds most modern waste handling unit, wastes will be air transported in an underground network of pipes to a collection point outside the hospital area. The closed system provides a better working environment and improves hygiene for both staff and patients, apart from raising safety and lowering operation costs.
Based on a patented solution for automated separation of wastes into four fractions (paper, incinerable waste, plastics and shredded paper), the system needs only one disposal inlet for all four fractions. On every floor level there is a disposal inlet point connected to the underground pipe network. When the button for the selected fraction is pressed, the waste is automatically source separated. Underpressure conveys waste to the collection terminal, where it is redirected into the proper waste category container.

The first part of the installation will be completed in the autumn of 2004. By 2014 the hospital plans to have 186,000 m2 of hospital facilities and handle 2,000 t/y of wastes

Contact: Mr. Joakim Karlsson, Marketing Manager, Envac Scandinavia AB, Sweden. Tel: +46 (8) 7753 200



New bio medical waste processor

Oxidation Technologies Inc., based in the United States, offers processing technology for the safe disposal of a wide range of medical wastes. Engineered to handle all types of medical wastes, including sharps, Bio-Oxidizer achieves 100 per cent destruction of pathogens, bacteria and viruses while reducing the waste mass by 95 per cent and volume by 99 per cent.

The system is based on the principle of electro-pyrolysis of organics and followed by two phases of electro-oxidation. Organic solids and liquids are electrically vapourized and the vapours are then oxidized in two oxidizers. The remaining residue, typically less than 5 per cent of the original weight and volume, is sterile, inert and can easily be discarded as municipal waste in most instances or, for example, possibly recycled as road aggregate. Key features are:

  • Fully automated loading and record keeping;
  • Enhanced safety;
  • Integral heat exchanger; and
  • Innovative control technology and interface.

Contact: Oxidation Technologies Inc., P.O. Box 548, Annapolis, MD 21404, United States of America. Tel/Fax: +1 (410) 9909 430/431



Technology to treat medical wastes

BGX Technologies LLC, the United States, is offering an effective technology for treating medical wastes linens, dressings, needles, food items, blood and tissue samples, medications, instruments and lab and surgical waste. Utilizing BGX technology, small low-power units can be set up in various areas of a facility where medical waste is produced. The systems reduce waste into its elemental, non-hazardous components that can be eliminated through conventional waste disposal facilities. The high temperatures at which a BGX system works, along with its ability to function in a system isolated completely from the atmosphere are the key components of this technology. The unit operates silently without producing offensive waste streams.

The systems can be constructed in a variety of shapes and sizes. Waste is deposited through an opening at the top. Control panel and indicators are situated on the front portion. Residue from the waste destruction accumulates in a heavy wall plastic bag at the base, which is removed as necessary. The systems operate under vacuum and do not use hydrocarbon fuel.

Contact: BGX Technologies LLC, 18, Broadway #133, Saranac Lake, NY 12983 1702, United States of America. Tel: +1 (518) 8918 929; Fax: +1 (518) 8919 630




Recycling of used home appliances

Hitachi Ltd., Japan, offers a system for recycling waste electric home appliances. Components like refrigerator compressors, which are hard to crush at room temperature, are crushed at 98 per cent separation ratio using low temperature brittleness. Metals such as iron, copper and aluminium are recovered with high purity from crushed waste using a highly efficient metal separation system. CFCs in compressor with oil and CFCs in insulation are sorted and separated. Urethane foam used as an insulation material is sorted by an air sorter, crushed into small grains, degassed, condensed and liquefied.

The system can also recycle office furniture and equipment, gas instruments, vending machines, etc.

Contact: Hitachi Ltd., 4-6, Kanda Surugadai, Chiyoda-ku, Tokyo 101 8010, Japan. Tel/Fax: +81 (3) 5295 5804/3258 9747



End-of-life disposal for electronic gadgets

Resources Concepts, the United States, has developed new technologies for recycling end-of-life (EOL) computers and electronic gadgets. Waste equipment are placed in a pre-shed area to inspect for toxic materials such as batteries, oil-filled capacitors that may contain PCBs, mercury containing components like switches or fluorescent lamps and any other toxic components. Following inspection and the removal of hazardous constituents, waste is sent through a gross shredder where it is reduced into small pieces.

Each component of the shredded material is manually segregated plastic, wire and cable, non-ferrous metals, circuit boards, paper, etc. and sent to their respective recycling outlets for reuse. A patented procedure separates and recycles both metal (gold, silver, platinum, palladium and copper) and non-metal components (thermoset plastic and coated fibreglass base board) of circuit boards and printed wiring assemblies. This method can also process bare boards and bare board trims to remove metals (high-purity copper) and non-metallic fractions (such as thermoset plastic-coated fibreglass).

Monitors and terminals are manually disassembled and the hazardous cathode ray tubes (CRTs) separated from other materials printed wiring boards, plastic, ferrous and non-ferrous metals, yokes and cables which are recycled through their respective processes. CRTs are sent through processing equipment where they are crushed into shards and metals are automatically separated from the lead-contaminated glass. Metals are sent to a metal refiner for recycling while glass is passed on to a lead refiner where lead is extracted and recycled. All the recycling processes are completely dry, chemical-free and do not involve incineration. Resources Concepts has obtained six patents for its proprietary EOL processing technique.

Contact: Resource Concepts, 2940, Eisenhower, Carrollton, TX 75007, United States of America.


New chemical recycling process

At the Institute for Energy Utilization, Japan, researchers are studying a chemical process for recycling electric-electronic devices. Plastics in these wastes are dehalogenated by liquid phase cracking at 400-440C using hydrogen donor solvent like tetralin. Halogen content in the gaseous and liquid products is reduced to less than 2 ppm using an alkali carbonate catalyst. Bromine in the solid product is fixed as alkali salts and can also be separated from metal by conventional washing with water. This indicates that halogen, resins and metal can be almost completely segregated and reused for chemical, fuel and material uses, respectively.

Contact: Mr. Yoshiki Sato, Institute for Energy Utilization, Kanazawa University, Japan.



Extracting value from PCB wastes

In the United Kingdom, a consortium of companies led by C-Tech Innovation has designed and tested a bio-electrochemical reactor to recover precious metals from waste printed circuit boards (PCBs). Developed under the BETSCRAP project, the reactor utilizes the unique properties of sulphur-metabolizing microbes to reclaim precious metals in either crop quantities or new nano-scale forms, with the potential for novel catalytic applications.

Normally, Desulphovibrio desulphuricans metabolizes through the reduction of geological sources of sulphur, yielding hydrogen sulphide. However, if it is starved of sulphur and prompted by electrochemically provided hydrogen, Desulphovibrio desulphuricans will instead reduce any precious metal ions present in its environment. Initially, precious metals will nucleate as nano-scale clusters, barely visible black dots at the cell walls in an electron micrograph.
Such nano-scale forms are unattainable by traditional chemical deposition methods and have huge potential as novel catalysts. If deposition is allowed to continue, the seed precious metal clusters start to auto-catalyse the deposition of further precious metal by a chemical route.

Large quantities of precious metals can be practically recovered, with the overloaded biomass eventually settling by gravity, where it can be harvested.

Contact: C-Tech Innovation, Capenhurst Technology Park, Capenhurst, Chester CH1 6EH, the United Kingdom. Tel: +44 (151) 3472 900; Fax: +44 (151) 3472 901



E-waste solution

In Canada, Maxus Technology Inc. has developed numerous processes for completely recycling electronic waste (e-waste). The MeWa e-waste processing technology can recycle all consumer electronic equipment, limited only by the material size and weight. Preparation of the material is limited to removal of toner cartridges. Batteries, capacitors and other such encapsulated hazardous components need not be removed, since these are not sheared or cut but the complete units are removed as a part of the sorting procedure. Monitors and TVs are prepared for processing by removing the CRTs, which are processed in a separate glass-to-glass recycling unit, and the remaining components processed in the QZ system.

Material that is selected and prepared for recycling is loaded directly into the in-feed hopper of the processing line utilizing a forklift with rotating forks. The material is conveyed into the MeWa QZ shredder in which a spinning chain imparts energy to the material, creating a cyclonic mixing action. The compound material co-shears, liberating the components from one another. The output material is sent across a magnetic separator feeding two parallel sorting stations, where the valuable components are retrieved and a small portion of the material is returned to the input of the processing line for further shredding. The output material, e.g. plastic, steel, circuit boards and non-ferrous metals, is transported and sold. Key benefits provided by the MeWa process over conventional methods are:
  • Processing capacities of around 4,081 kg/h, or 32,653 kg/d utilizing only marginally increased labour input (as is presently needed for about 10 per cent of this amount);
  • Significantly lower capital costs, by a factor of at least half, when compared with similar capacity e-waste processing machinery;
  • Reduced maintenance costs (80 per cent) than traditional shredding machinery;
  • Increased margin on processed material due to less co-mingling of the valuable commodities with non-value streams;
  • A mobile platform that allows relocation of the entire processing line to ensure machinery is operated at high capacity; and
  • Modular construction allows for expansion of the processing line to achieve higher capacity and incorporation of new technology for monitor and TV processing, including glass treatment.


Recycling technology for waste electronics

Electronics Partners Corp. (ePC), the United States, offers a breakthrough technology solution which could revolutionize the economics, environmental integrity and volume capacity for electronics end-of-life management. The new proprietary mechanical separation can take in all types of electronic products and systematically convert the e-waste into valuable resources like plastic, fibreglass and metals. An overview of ePCs technology is given below:

  • Automation results in unprecedented volumes:
    * 1.362.26 million kg/month/ plant; and
    * Equivalent to 200+ employee demanufacturing crew;
  • Pure and homogeneous streams drive more consumer choices and higher constituent return;
  • Proprietary system customized to ePC specification:
    * Process needs for handling electronics;
  • Operational variables controlled by software:
    * Each product category optimized and stored;
  •  Technology solution best delivered as a managed service:
    * Serves entire recycling ecosystem;
  • Operation includes:
    * 35 air unit control variables;
    * 11 centrifugal controls;
    * 19 motor control computers;
    * Six material mass control variables; and
    * Ability to deliver 13 material output streams.

Contact: Electronics Partners Corp., Corporate Office, 724 Castle Creek Dr., Coppell, Texas 75019, United States of America. Tel: +1 (972) 3938 045; Fax: +1 (972) 3938 154



Activated carbon bed recovery system

Dec-E-Tech Inc., the United States, is offering solvent recovery systems based on activated carbon bed. The new systems use steam to remove solvents from the carbon bed. Steam contaminated with pollutant vapours is condensed so that the organics and water can be separated through gravity decantation or distillation. Three unit systems allow for one bed to cool after steam regeneration and before it is placed back into service. Key features of the activated carbon bed solvent recovery unit include:

  • Modular design allows for single or multiple adsorbers;
  • Uses filter, fan with VFD, cooling coil, adsorber, reactor and decant system with boiler, if required;
  • Typical system efficiency surpasses 98 per cent;
  • Inlet solvent saturation level up to 50 per cent LEL;
  • Fault indication system;
  • Inlet filter;
  • Single switch operation;
  • Cooling tower and coils;
  • Tanks for temporary storage of solvents; and
  • Distillation column available.

The company is also offering Inert Atmosphere Turbosolve I driers and CM Technologies ASRS solvent recovery units with low temperature condensation. The inert atmospheric systems allow for very high levels of solvent in the drier owing to the nitrogen atmosphere especially certain coating applications with high solvent loads. Production of adhesive tape, magnetic tape, speciality films and foils and metal coil coating could benefit from this technology. Advantages of this system include:

  • Recovery cost ratio is 3:1 to that of activated carbon systems;
  • Lower secondary emissions;
  • Higher level of safety for high solvent loads;
  • No effect on product quality; and
  • Recovered solvent is less contaminated.

Contact: Dec-E-Tech Inc., 5, Progress Avenue, Tyngsborough, MA 01879, United States of America. Tel: +1 (978) 6493 285; Fax: +1 (978) 6498 866



Recycling system for sheet-fed printer

In Canada, Maratek Environmental is offering a system for reclaiming solvents from sheet-fed printers that employ automatic blanket washers. Waste solvent or blanket wash from sheet-fed presses present serious environmental concerns. The SRS solvent recycling system supplied by Maratek is flexible and designed to work with the majority of solvents and blanket washes available in the marketplace. Specifically, it is designed to work with water-miscible solvents which may be coming off auto-washer sheet-fed presses. No VOCs are used while recovering up to 95 per cent of the solvent to produce virgin quality wash for reuse. Additionally, hazardous waste hauling costs are reduced by 95 per cent.

Contact: Maratek Environmental, 60, Healey Road, Unit 8, Bolton, ON L7E 5A5, Canada. Tel: +1 (800) 6676 272; Fax: +1 (905) 8572 764



Solvent recovery by vapour permeation

Hovione, Azores, has developed new vapour permeation technology to recover solvents. The vapour permeation system is based on membrane technology and has two sub-units:
  • An evaporator equipped with a high efficiency demister to remove non-volatile impurities; and
  • A group of linked hydrophilic
    membrane modules, gas permeation (sub-units), to separate water from the solvent through vapour permeation.

In an analogous procedure to pervapouration, the membrane modules are located in a vacuum chamber that acts as collector and condensation system for the permeate mixture exiting as vapour from the backside of the membranes. However, vapour which is fed to the membranes is dehydrated and not a heated liquid.

Contact: Hovione, Departamento de Reciclagem e Tratamento de Produtos Secundarios, Quinta de S. Pedro - Sete Casas, 2674 506 Loures, Azores. Tel: +351 (21) 9829 280; Fax: +351 (21) 9829 289



Regenerating solvents

Fercell Engineering Ltd., the United Kingdom, is offering new systems to regenerate dirty solvents. Solvent Reclaimers operate on the principle of distillation. The working cycle is completely automatic and controlled by a printed circuit based on the vapour temperature read-out. The solvent to be recovered is poured into a stainless steel tank and brought to boil using diathermic oil in the outer casing. Solvent vapours separate from the pollutants, i.e. grease, ink, paint, pigments, resins, etc. They then pass through the cooling battery where they are condensed by cool air flowing from a fan. Clean solvent flows out of the discharge pipe into an appropriate container. Residues remaining in the tank can be removed using special distillation bags, facilitating quick and easy cleaning.

Contact: Fercell Engineering Limited, Unit 1, Old Mill Lane, Aylesford, Kent ME20 7DT, United Kingdom. Tel: +44 (1622) 791 414; Fax: +44 (1622) 791 515



High-volume recyclers

Recycling Sciences Inc., the United States, offers industrial distillation systems for recycling high volume solvent waste streams in distinct batches. The batch systems range in size from the RSI-14, with a 64 l batch distillation tank, to the RSI-55 with a 250 l tank capacity. Each unit can recycle a variety of solvents used in most industrial processes, through heat distillation. All industrial systems are designed for the safe recovery of volatile and inflammable solvents. Moreover, these units can pay for themselves in less than six months. Notable features of the RSI-14, RSI-23 and RSI-30 portable systems include:
  • Rugged construction using stainless steel;
  • Caster mounted for easy portability;
  • Safe electrical design;
  • Explosion proof design;
  • Fast solvent recovery rate;
  • 30 inch cord, 240 V circuitry and heater;
  • Simple to operate two button operation;
  • Automatic operation: unattended system shut-off on completion; and
  • Water-cooled condensers.

In all the solvent recovery systems, depending on the contaminate of the solvent, the residue can either be contained in a high temperature cooking bag or easily wiped out of the shiny stainless steel tank.

Contact: Recycling Sciences Inc., 16619, Wikiup, Ramona, California 92065, United States of America. Tel: +1 (760) 7899 341; Fax: +1 (760) 7870 249



New fluid bed concentrator

In the United States, Environmental Compliance Technologies Inc. offers fluid bed VOC control and solvent recovery systems which provide a proven and cost-effective method applicable to a variety of industrial and commercial applications. This technology guarantees a practical means to treat high volume, low-VOC concentration process gas flows. The system can achieve flow volume reduction ratios from 1,000:1 to as high as 10,000:1, allowing for several highly economical final treatment options. System sizes range from 200 scfm to over 100,000 scfm, with removal/recovery rates exceeding 95 per cent.

Since the launch of the worlds first practical fluid bed VOC recovery system in the 1970s, the company has been modifying and improving on both the design of the fluidized bed technology and fundamental techniques of adsorbent regeneration and reactivation. Recent developments include commercialization of a new regeneration technique, which incorporates the most highly energy efficient process to date. The new regeneration process operates at a higher temperature than earlier technologies, thus reducing the need for carbon reactivation.

Contact: Environmental Compliance Technologies Inc., United States of America. Tel: +1 (518) 2742 650; Fax: +1 (518) 2745 454



Energy from waste solvents

LTG Air Purification Systems, the United Kingdom, offers an air purification system that operates itself and the production process using surplus solvents. Working together with Freudenberg, Germany-based manufacturers of non-woven fabrics, LTG evolved a system which takes exhaust air from curing processes at Freudenberg and oxidizes the large amount of solvent it contains, thus producing high-temperature clean air. This air, containing all the energy liberated from the solvents, is then passes through a waste heat boiler to produce 6 t/h of steam, which is piped back to the primary production process, as such closing the energy loop.

Contact: LTG Air Purification Systems, 55 Winter Hey Lane, Horwich, Bolton, Lancashire BL6 7NT, United Kingdom. Tel: +44 (01204) 668 606; Fax: +44 (01204) 668 450.



Catalytic oxidizers

Air Pollution Solutions, the United Kingdom, offers Thermocat catalytic oxidizer system for treating polluted gas streams. Waste air enters the system and moves over a cross-flow type plate heat exchanger, where outgoing combustion gases heat it. The heated gas stream passes into a combustion chamber where it is heated to the oxidation temperature, typically 350C. It then passes over a catalyst bed, where the rate of decomposition of organic compounds is increased tenfold at temperatures lower than in a conventional oxidizer. Heat recovered from the clean hot air that is vented out helps lower fuel consumption.

Thermocat systems are relatively smaller and lighter than equivalent units. Traditional thermal oxidizers work at 800C or more, which need more fuel for the process and heavier gauge material for construction.

Contact: Mr. David Foxen, Air Pollution Solutions, Colt House, New Lane, Birmingham B1 1QQ, the United Kingdom. Tel: +44 (121) 2141 300; Fax: +44 (121) 2002 555



TPI News, Issue 41, Spring 2004

Degrading air pollutants

Air pollution control systems offered by ABC Environmental, the United Kingdom, are based on controlled microbial biodegradation of the contaminants using naturally occurring bacteria and fungi. Micro-organisms in ABCs bioreactor grow as biofilms on a mixed support media where they produce enzymes. Here, they break down VOCs by mineralization and use some of the carbon for biomass growth. So, once established, they need not be replaced. Liquid is recirculated within the bioreactor to wash solvents from the tainted inlet gas and novel media are specifically selected to provide effective contact between the vapour phase and liquid phase, avoiding clogging.

Contact: Mr. Richard Ambrose, ABC Environmental, Innovation Buildings, Sittingbourne Research Centre, Sittingbourne ME9 8HL, the United Kingdom. Tel/Fax: +44 (1795) 411 550/551



TPI News, Issue 41, Spring 2004

New technology for emission control

The United States-based Kleanaire Technology LLC offers technology to improve the removal of particulate matter (PM), acidic gases and heavy metals from emissions by means of continuous control of independent filtering chambers. Each chamber provides individual control over the separate processes of cleaning, pre-coating with sorbent material and filtering. This allows optimization of emissions collection efficiency, cost and prevent fugitive emissions.

Conventional dry flue gas scrubber technology is inefficient because of spikes in emissions, which occur during baghouse cleaning cycles. To remove cleaning spikes Kleanaire utilizes a method and device known as Emissions Terminator. This system employs long-known methods difficult to implement without pretreatment methods such as electrostatic precipitators or pre-filter systems adding to costs. Kleanaire technology advances the process of air pollution control through the implementation of clean atmosphere for coating without a pretreatment system. Terminator allows for the following improvements:
  • A thin coating can be applied to the surface of any filter media under selection, which is known to improve filter capture rates of PM;
  • Efficient use of sodium bicarbonate as a reagent sorbent alkaline proven in the incineration arena to be highly effective in PM, acids, metals and VOCs on levels that rival active carbon at less cost;
  • A clean air pre-coating application system which is able to apply selective sorbent upon individual filter sections for the development of a sorbent coating without allowing pollutant gases to pass through, thus eliminating cleaning spikes;
  • Definitive air flow control through individual filter segments which are able to lower air flow rates during pre-coating and preventing:

    * Injected sorbent particles from being drawn through the fabric of the woven filter media by high air velocities after cleaning; and
    * Filter cloth wear from abrasion between the filter media and support cage, resulting in longer filter life.
  •  Having multiple sorbent injection points provides the ability to:

     *  Apply powdered limestone as body feed sorbent   
         supplied during flue gas processing;
     *  Apply sodium bicarbonate or activated carbon as  
         a pre-coat to reduce cost and increase   
         efficiency; and
     *  Apply a 1~4 mil thickness of pre-coat outside the
         hot, contaminated flue gas stream known to   
         protect filter media from heat and deterioration 
         from acids.

Contact: Kleanaire Technology LLC, 111, Sycamore Street, Bay St. Louis, Mississippi 39520, United States of America. Tel: +1 (228) 4665 004; Fax: +1 (228) 4666 035



Novel scrubber

Advanced Air Technology Inc. (AATI), the United States, offers Variable Multiple Throat for applications requiring a constant outlet emission rate over a wide range of changing inlet operating conditions, including volume, temperature and particulate loading. The patented design allows the venturi openings to be adjusted either pneumatically or mechanically without compromising the principle of paralleled throat venturi scrubbing. The Variable Multiple Throat comprises two sets of elements, one fixed and one variable. The lower set of elements form an array of inserts that move up and down between the fixed set of wall components, varying the spacing between them. This variable spacing allows a fine-tuned resistance to gas flow since the movement of inserts changes the venturi cross-sectional area.

The Multiple Throat Scrubber (MTS) offers outstanding flexibility in layout, installation and operating efficiency. The scrubbers fixed elements work efficiently at low operating pressure to minimize costs. MTS operates with 3-15 gpm/1,000 cfm of gas, depending on the application requirements. Salient features include:
  • Can be utilized for upgrading inefficient or obsolete pollution control equipment, or reduce maintenance costs on an existing scrubber;
  • Water distribution problems are eliminated regardless of flow rate and pressure drop;
  • The wear zone is reduced to the easily replaceable elements alone;
  • The design has been proven in hundreds of applications throughout industry; and
  • The MTS design can be used for varying process flows by adding a simple variable throat mechanism.

AATI also offers dual throat venturi scrubber, one of the most advanced and particulate scrubber.

Contact: Advanced Air Technology Inc., 3105, North Wilke Road, Suite X, Arlington Heights, Illinois, IL 60004, United States of America. Tel: +1 (847) 3949 553; Fax: +1 (847) 3949 757



New electrostatic precipitators

Sumiko Engineering Co. Ltd., Japan, is offering electrostatic precipitators (ESPs) in which the distance between the electrodes is wider than found in conventional ESPs, while also utilizing a high voltage system. This space between the electrodes helps reduce the number of components and allows for inspection during maintenance. Extremely fine dust particles can be captured, unlike in conventional ESPs. The firm offers both wet and dry type ESPs.

ESPs offered by another Japanese company, Kyowa Kako Co. Ltd., incorporate a peculiar structure that makes use of pipes for the discharge electrode as well as dust collecting electrode (patent-pending). Additionally, they have a two-stage structure in which the charging element and dust collecting element are separately provided in the same room. Salient features of these are:
  • The two-stage reverse ionization phenomenon helps dust having high resistance to be collected efficiently;
  • Two-stage structure and Karman vortex by pipe arrangement lowers deterioration of the dust collecting efficiency or fresh scattering phenomenon of dust;
  • Since active stable corona discharge can be anticipated by adopting a fish bone-shaped discharging needle, dust may be supplied with sufficient charge;
  • Absorption of inversely charged dust particles by the electrode may prevent deterioration of the dust collection efficiency;
  • Large field strength can easily be obtained by a pipe auxiliary electrode of the discharging pole; and
  • If corrosion resistance is needed, manufacturing with SUS, PVC, FRP material is possible.

Contact: Sumiko Engineering Co. Ltd., Japan.


Or Kyowa Kako Co. Ltd., Japan.



System to regulate emissions of SO2

Andersen 2000 Inc. of the United States and Montair Andersen bv are offering three types of sulphur dioxide (SO2) removal systems. First is a packaged system for industrial boilers, industrial plant exhausts, metal smelting operations and small utility plant steam boilers burning coal or oil. This system uses either sodium hydroxide or sodium carbonate to absorb SO2. A patented low-energy spray-baffle scrubbing unit or venturi scrubber is used if the gas stream contains particulates. In the absence of particulate matter in the exhaust gas stream, a counterflow packed bed scrubber can be used. For larger industrial sources and utility plants, a double alkali SO2 removal system is offered. This unit can be combined with particulate collection scrubbers for coal-fired sources or connected to the discharge from a electrostatic precipitator or fabric filter.

The third system, spray-baffle type low-energy scrubber, is for oil-fired sources. Here, SO2 is absorbed into a sodium sulphite solution and the resultant bisulphite is transformed back into sodium sulphite by adding a calcium precipitating agent. Precipitated calcium compounds are then filtered from solution and disposed as dry solids. Several package units are available for smaller sources and custom-designed units can be built for high emission rates.

Contact: Andersen 2000 Inc., Incineration and Air Pollution Control, 306 Dividend Dr., Peachtree City, Georgia 30269, United States of America. Tel: +1 (770) 4862 000; Fax: +1 (770) 4875 066.


Air pollution control systems

In Japan, Sasakura Engineering Co. Ltd. is offering a hot gas filter for the conversion of exhaust gas streams into clean gas at high temperatures to utilize heat energy and control air pollution. The LLB hot gas filter is based on technology developed by LLB Lurgi Lentjes, Germany. This unique and reliable hot gas filter is a key component of next-generation power plants.

Also available are high-temperature bag/ceramic filters to clean dust at around 800C in a high temperature environment to yield clean gas. The EC fume control unit is for handling the temperature of exhaust fumes from press-out laminating machines and pellet manufacturing equipment while collecting melt down fumes. It prevents air pollution and accumulation of resinoid fumes.

Contact: Sasakura Engineering Co. Ltd., 7-32, Takejima 4-chome, Nishiyodogawa-ku, Osaka 555 0011, Japan. Tel: +81 (6) 6473 2131; Fax: +81 (6) 6475 2899.


New oxidizer range

Thermtech Inc., the United States, is offering catalytic oxidizers and regenerative thermal oxidizers with capacities varying from 100 scfm to 30,000 scfm. Catalytic oxidizers offer destructive efficiencies from 90 to 99.99 per cent, while thermal oxidizers destruction efficiencies are more than 99 per cent, operating temperatures of 1,150C and retention times as required to achieve the desired results. Heat exchangers are also available to ensure more economical operating costs.

Thermtechs unique Enclosed Flare system for barge and tank loading facilities operates at about one-third the cost of a typical flare system. This state-of-the-art system utilizes diluting technology that is fully automated to offer the ultimate in safety while automatically modulating fuel and air requirements as the process conditions change. Fixed bed concentrators/DeZorbers designed for high flow processes with low VOC concentrations are also available with capacities up to 50,000 scfm. PLC-controlled desorb systems combine adsorption with oxidation technology to offer the lowest operating cost per cfm in the industry.

Other systems being offered include recuperative catalytic thermal oxidizers, catalytic thermal oxidizers, recuperative thermal oxidizers, regenerative thermal oxidizers and air pollution control systems.

Contact: Thermtech Inc., 808, Russell Palmer Road, Kingwood, TX 77339, United States of America.
Tel: +1 (281) 3597 555; Fax: +1 (281) 3597 550



Fume treatment

Solios Environnement SA, France, offers high-performance technology for treating fumes. The fume treatment centres (FTCs) are designed to meet the following objectives:
  • Comply with the most stringent emission requirements;
  • Protect the filter bags by cooling fumes to a constant temperature;
  • Prevent pluggage of ductwork resulting from high concentration of tars and dust; and
  • Avoiding wetting of the walls and bottom of the evaporative cooling tower that cause severe corrosion.

For open type bake furnaces, FTCs incorporate the following features:

  • Cooling of gases in a specially designed down-flow evaporative cooling tower. Adsorption of tars and HF with injection of fresh and recycled alumina;
  • Modular design for continuous operation at full capacity;
  • Balance gas distribution to each module;
  • Precise alumina as well as fume control for each module;
  • Large fluidized hoppers to store alumina and continue alumina recycle by overflow;
  • Gentle bag cleaning with low pressure pulse with patented specified IAP valve; and
  • Security and ergonomic working conditions for operators.

VJC type venturi scrubber offered by the company is a downflow venturi designed with the proper liquid rate (adjustable) and pressure drop to meet the desired particulate removal efficiency. It is used exclusively for particulate collection (even very fine) and its spraying rate is moderate. The venturi throat is provided with one or several patented LJC spray nozzles that feature two co-current jets that produce the fine atomization while the nozzles openings are large enough to prevent plugging or wear with the recycle solution being sprayed. The throat can be provided with an adjustable damper to allow operation at different flow rates while maintaining the same efficiency.

The venturi VJC is generally coupled with a separate mist eliminator or a Granivore-Cyclopal. It is an integral part of a complete treatment system and has a flow rate between 15,000 and 180,000 m3/h.

Contact: Solios Environnement SA, 25-27, Bd de la paix, 78100 Saint-Germain-en-Laye, France. Tel: +33 (1) 3087 4550; Fax: +33 (1) 3087 4555.


Systems to help mitigate air pollution

F.L. Smidth Airtech A/S designs, manufactures and installs a variety of air pollution control equipment. While dry electrostatic precipitators (ESPs) are well-known for their high efficiency and low operating costs, wet ESPs are common in the metal roaster industrys sulphuric acid plants and petrochemical facilities. The modern HEX designs, made of alloys, are ideal for these industrial applications.

Gas suspension absorbers (GSAs) are highly efficient in the process utilization of lime slurry. A major reason is that the reactor is based on gas suspension technology, i.e. very large concentration of fly-ash, dust particles and lime builds up inside the reactor. The FabriClean Pulse-Jet Fabric Filters offer high efficiency dust collection with low maintenance. Other products available are gas conditioning towers, wet flue gas absorbers, bag houses and multi-pollution control units.


NOx abatement by combustion

Hitachi Zosen Corp., Japan, offers a high performance super low NOx system that integrates an ordinary combustion type burner and 3-stage patented combustion type low NOx system. Normal oxidizing combustion occurs in the primary combustion zone where most of the fuel burns and combustion efficiency is very high. Unburnt parts from the secondary fuel in the secondary combustion zone is burnt in the tertiary combustion zone. As such, combustion efficiency in the 3-stage low NOx boiler is on par with ordinary boilers without NOx reduction.

In the case of 3-stage combustion, reducing combustion is limited only to the secondary combustion zone, so that reducing atmosphere space is very narrow. Furthermore, since measures are taken so that combustion gas with a strong reducing capability does not directly strike the water wall, adverse effects from things such as reducing corrosion and slagging on the heating surfaces inside the furnace due to reducing atmosphere, even in case of super low NOx combustion, are extremely small compared with other NOx reduction units like OFA combustion system, which expose a large part of the furnace inside to reducing atmosphere.

Contact: Hitachi Zosen Corp., Japan.




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