Co-firing of paper sludge with high-calorific industrial wastes in a pilot-scale nozzle-grate incinerator

Experiments on the co-firing of high-calorific industrial wastes with paper sludge were performed in a pilot-scale industrial waste incinerator with a nozzle-type grate system. The incineration capacity was approximately 160kg/h. The temporal variations in the temperatures and exhaust gas emissions were monitored and used as parameters for determining the desirable incineration conditions. The high CO emissions that were mainly due to the rapid vaporization of combustibles from high-calorific industrial wastes could be alleviated through the co-firing of sludge with the high-calorific industrial wastes. Because of the high nitrogen content in the sludge, the increase in the co-firing rate caused higher NO emissions in the flue gas. If the total calorific value of the feed was lower than 750,000kcal/h, for 25-30% of sludge co-firing, the temperature of gases exiting the secondary combustion chamber might be lower than that required by regulations.     

Gaseous emissions from waste combustion

An overview is given on methods and technologies for limiting the gaseous emissions from waste combustion. With the guideline 2000/76/EC recent European legislation has set stringent limits not only for the mono-combustion of waste in specialized incineration plants but also for co-combustion in coal-fired power plants. With increased awareness of environmental issues and stepwise decrease of emission limits and inclusion of more and more substances into the network of regulations a multitude of emission abatement methods and technologies have been developed over the last decades. The result is the state-of-the-art waste incinerator with a number of specialized process steps for the individual components in the flue gas. The present work highlights some new developments which can be summarized under the common goal of reducing the costs of flue gas treatment by applying systems which combine the treatment of several noxious substances in one reactor or by taking new, simpler routes instead of the previously used complicated ones or - in the case of flue gas desulphurisation - by reducing the amount of limestone consumption. Cost reduction is also the driving force for new processes of conditioning of nonhomogenous waste before combustion. Pyrolysis or gasification is used for chemical conditioning whereas physical conditioning means comminution, classification and sorting processes. Conditioning yields a fuel which can be used in power plants either as a co-fuel or a mono-fuel and which will burn there under much better controlled conditions and therefore with less emissions than the nonhomogeneous waste in a conventional waste incinerator. Also for cost reasons, co-combustion of wastes in coal-fired power stations is strongly pressing into the market. Recent investigations reveal that the co-firing of waste can also have beneficial effects on the operating behavior of the boiler and on the gaseous emissions.     

Efficient waste-to-energy system as a contribution to clean technologies

This paper deals with the problem of efficient energy utilization in the field of thermal processing of waste (waste-to-energy). An up-to-date incineration plant cannot be considered as only waste disposal facility. The waste combustion (incineration) processes are accompanied by release of large amount of energy, that shall be effectively utilized (e.g. steam production and its export to consumers, power generation, cogeneration). In addition to the main purpose of incineration, i.e. treating the specified amount of waste, waste-to-energy systems are able to some extent substitute conventional energy production plants fired by fossil fuel and thus to contribute to solving global environmental problems. For example, methodology presented in Reference Document on the Best Available Techniques for Waste Incineration (BREF) can be used for assessment of plant performance from the view of energy utilization. This approach is based on evaluation of criterion Plant Efficiency. An existing incineration plant has been evaluated and results are presented and discussed. In the future, it has been expected that evaluation like this will be obligatory for every plant. The arrival of more and more sweeping environmental limits represents a driving force for retrofit. At the same time maximum heat recovery and efficient energy utilization should be required. Influence of different operational modes (type of waste incinerated, combustion temperature, air-preheating etc.) and lay-out of heat recovery system (e.g. cogeneration) on plant performance has been investigated. A mathematical model based on combination of basic auxiliary operations and simple thermodynamic models of heat engines has been created with the aid of a specific computational tool. Its conception is based on both requirements and experience coming from industry. The most serious problem of effectively running incineration plants consists in economical utilization of energy produced. Examples of integration into existing energy systems are shown and discussed. An erratum to this article can be found at     

Demonstration plasma gasification/vitrification system for effective hazardous waste treatment

Plasma gasification/vitrification is a technologically advanced and environmentally friendly method of disposing of waste, converting it to commercially usable by-products. This process is a drastic non-incineration thermal process, which uses extremely high temperatures in an oxygen-starved environment to completely decompose input waste material into very simple molecules. The intense and versatile heat generation capabilities of plasma technology enable a plasma gasification/vitrification facility to treat a large number of waste streams in a safe and reliable manner. The by-products of the process are a combustible gas and an inert slag. Plasma gasification consistently exhibits much lower environmental levels for both air emissions and slag leachate toxicity than other thermal technologies. In the framework of a LIFE-Environment project, financed by Directorate General Environment and Viotia Prefecture in Greece, a pilot plasma gasification/vitrification system was designed, constructed and installed in Viotia Region in order to examine the efficiency of this innovative technology in treating industrial hazardous waste. The pilot plant, which was designed to treat up to 50kg waste/h, has two main sections: (i) the furnace and its related equipment and (ii) the off-gas treatment system, including the secondary combustion chamber, quench and scrubber.     

Emissions investigation for a novel medical waste incinerator

Medical waste constitutes one of the waste streams that should be dealt with special priority due to its potential negative impact on public health and on the environment. Incineration is a process that is widely used for the treatment of medical waste. However, self-supporting combustion of medical waste cannot avoid releasing many hazardous pollutants into our environment. The most favored solutions are firing additional fuels of high calorific value and direct purification by air pollution control devices (APCD). This process entails not only large first time investment but also an increase in the operation cost. A novel incinerator is proposed for better utilization of energy of the incineration process. Its originality is essentially due to combining a feeder, a rotary grate, a cylindrical gasifier and a “coaxial” secondary combustion chamber into a unique unit. The structure of the incinerator as well as the principle of the incineration process is presented in this paper. A full-scale trial of the novel incinerator with APCD was carried out from March to May 2008 to investigate how the distinct configuration influenced the incineration process. Data on PM, CO, NO_X, O₂ were recorded by a continuous emission monitoring system during the study period. Heavy metals and PCCD/Fs were also sampled and measured. Measuring results were compared with the China and U.S. EPA guidelines. The concentrations of contaminants were below their respective limits in emission control standards. Results from testing the novel medical waste incinerator confirmed that this technology has a good suitability for neutralization of medical wastes and purification of flue gases.     

Applying industrial ecosystem indicators: case of Pielinen Karelia,Finland

This paper presents an industrial ecological insight into local waste management in Pielinen Karelia, Finland. There local system is experiencing major changes because of tightening EC waste legislation including the directives on waste incineration (2000/76/EC) and landfilling of wastes (1999/31/EC). Small local landfills are closing and most of municipal wastes will be transported 120–180 km to large-scale waste management centre in Kuopio. The paper applies three industrial ecosystem indicators, based on environmental, economic and employment impacts of different waste management technologies. Environmental indicator is CO₂ equivalent emission, economic indicator is based on costs and revenues of waste management, and social (i.e. employment) indicator includes new jobs generated. The results indicate that waste incineration option in forthcoming regional cooperation could create emission savings up to 117–394 kg CO₂ eqv./ton of municipal waste when compared to local landfilling. As economic impacts, new regional cooperation and long-distance transportations will increase the costs from previous 45.6–55.2 €/ton in local landfilling to 97.4 €/ton in regional landfilling and 120.8–126.9 €/ton in regional REF-III incineration. In terms of employment, the new cooperation could create 2–6.5 new jobs. The regional cooperation results to rising operational costs but avoids investments to new local infrastructure. It also creates significant emission savings, maintains current employment in waste handling and creates new jobs in long-distance transportation.

Thermodynamic Analysis of the Gasification of Municipal Solid Waste

This work aims to understand the gasification performance of municipal solid waste (MSW) by means of thermodynamic analysis. Thermodynamic analysis is based on the assumption that the gasification reactions take place at the thermodynamic equilibrium condition, without regard to the reactor and process characteristics. First, model components of MSW including food, green wastes, paper, textiles, rubber, chlorine-free plastic, and polyvinyl chloride were chosen as the feedstock of a steam gasification process, with the steam temperature ranging from 973 K to 2273 K and the steam-to-MSW ratio (STMR) ranging from 1 to 5. It was found that the effect of the STMR on the gasification performance was almost the same as that of the steam temperature. All the differences among the seven types of MSW were caused by the variation of their compositions. Next, the gasification of actual MSW was analyzed using this thermodynamic equilibrium model. It was possible to count the inorganic components of actual MSW as silicon dioxide or aluminum oxide for the purpose of simplification, due to the fact that the inorganic components mainly affected the reactor temperature. A detailed comparison was made of the composition of the gaseous products obtained using steam, hydrogen, and air gasifying agents to provide basic knowledge regarding the appropriate choice of gasifying agent in MSW treatment upon demand.     

A comparision of regulated chemicals versus emitted PICs and PICs for risk analysis

In general, toxic combustion byproducts (TCBs) are the unwanted residues remaining in flue gases, combustion ashes, and wastewaters from the operation of an incineration or combustion facility. If a combustor is not well designed and operated, it may emit too high a level of TCBs. Categories of TCBs and some example constituents are as follows:

1. 1. Acid gas: HCl, NO_x and SO₂;

2. 2. Organics: Hydrocarbons such as dioxins and furans (PCDDs and PCDFs);

3. 3. Particulates: Trace metals (conventional metals and radioactive metals) and soots;

4. 4. Contaminants in ash; and

5. 5. Contaminants in spent wastewater.

Pollutants in Category (2) above are generally considered to be the products of incomplete combustion (PICs) in the field of hazardous waste incineration.

TCBs has been one of the major technical and sociological issues surrounding the use of incineration as a waste treatment alternative. Because of the complexity and controversy, the U.S. EPA issued a draft “Combustion Strategy” on May 18, 1993. The objective of the “Combustion Strategy” was to address the needs of and to outline the approaches for upgrading the existing incineration standards to better control TCB emissions.

This article lists those chemicals and metals which are regulated by two major U.S. environmental laws, namely, the Clean Air Act Amendments (CAAA) of 1990 and the Resource Conservation and Recovery Act (RCRA) of 1976. The CAAA is to regulate the air emissions from major sources, and the RCRA is to protect human health and the environment from the management of solid wastes, particularly from waste incineration. This paper also lists the PIC chemicals that were studied under U.S. EPA incineration research programs in the 1980s and the PIC chemicals that EPA permit writers are considering be the subject of risk analyses during the process of industry's applying for an incinerator operating permit.     

Fluidized bed incinerator for medical waste that generates no residual dioxin: a mini-review

The advantages of medical waste incineration include the sterilization of bacteria, stabilization of chemical activity, and reduction in waste volume. During the incineration of medical waste, dioxin is generated owing to the high chlorine content. Based on previous research, a conventional fluidized bed combustor with a minimum retrofit to dispose of medical waste without residual dioxins is presented in this study. Coal or pyrite was added to inhibit dioxin formation in the combustion chamber. Fly ash and activated carbon which had adsorbed dioxin were pelletized with adhesive material, and the pelletized fly ash was then recycled to the incinerator for burning. The pelletized fly ash with adhesive material was finally discharged as bottom ash. Bottom ash constitutes the net output of the entire incineration system. and its dioxin content can be neglected. An incineration system that does not produce dioxin residue was achieved; however, a better formula for the pelletized fly ash is still required.

Title page (short abstract)

1. The emission of dioxin from medical waste incinerators can’t be eliminated by disabling PVC as a raw material of medical devices.

2. Based on the knowledge shown in the previous literature, an integrated fluidized bed incineration system without dioxin residual installed in a large hospital is proposed in this study.

3. There are many ways to reduce dioxin formation during the incineration process; however, conventional methods can’t eliminate the existence of dioxin in fly ash.

4. Pelletized fly ash recycled to the incinerator for re-burning and discharged in the form of bottom ash which is considered dioxin free.

     

Industrial ecosystem indicators—direct and indirect effects of integrated waste- and by-product management and energy production

In an idealised industrial ecosystem (IE), firms and organisations utilise each other's material and energy flows including wastes and by-products to reduce the system's virgin material and energy input as well as the waste and emission output from the system as a whole, and contribute to sustainable development (SD). IE complements the more conventional individual flow, product, process, organisation, individual actor or sector-focused environmental management approaches and tools with network or systems level approaches. The first research objective of this paper is to construct indicators for IE. The second task is to test the use of these indicators with "what if?" material and energy flow scenarios for the energy and waste system of Satakunta region in Finland including 28 municipalities. Using literature analysis as a source, we arrive at environmental indicators of carbon dioxide (CO₂) equivalents, and at economic indicators of fuel, energy and waste management costs and revenues. The social indicators show the employment effects of the waste management system. The scenarios analyse the current situation (0-scenario) against alternative situations in the future. The future scenarios are developed according to the known and anticipated trends in international and national policy and legislation. The indicator application in the scenarios produces social, environmental and economic effects of waste management in four categories: direct negative, direct positive, indirect negative and indirect positive. Industrial ecosystem theory emphasises the utilisation of wastes as a resource with value alongside the objective of reducing waste. Therefore, the indirect positive effects of waste management are important, as well as the conventional focus of waste management, which has usually been on direct positive effects. The main difficulties in our argument are the system boundary definition, the qualitatively different nature of environmental, economic and social effects and indicators as well as the lack of qualitative or interview data on the preferences and interests of the actors involved.     

Partitioning characteristics of targeted heavy metals in IZAYDAS hazardous waste incinerator

Partitioning of eight targeted heavy metals (Cr, Mn, Cu, Pb, Sn, Co, Ni and Zn) was carried out during five trial burns in Izmit hazardous and clinical waste incinerator (IZAYDAS). Metal contents of the original wastes and their concentration in the bottom ash (BA), fly ash (FA), filter cake (FC) and flue gas were determined. Partitioning behavior of metals during the two-stage incineration was evaluated with respect to physico-chemical properties of feed waste and metals, and the operational conditions. Results suggest that combustion temperatures and retention times are the dominant parameters determining the volatility of metals in the first combustion chamber. Targeted metals were generally partitioned in the rank of bottom ash, filter cake, fly ash and flue gas. High filter cake/fly ash ratios showed that high temperatures in the second stage increase both the formation of gaseous metallic compounds and the enrichment of metals in fine particles. Since ESP could not be effective in removing fine particles and volatilized metallic compounds, the necessity of an additional system that would remove heavy metals efficiently was emphasized for the modern incinerators.     

Sources, characteristics and treatment and disposal of industrial wastes containing hexachlorobenzene

Hexachlorobenzene (HCB) is a hazardous component of certain industrial wastes. The hazardous characteristics of HCB stem from its toxicity, potential for bioaccumulation and environmental persistence. A study was conducted to identify the sources and characteristics of manufacturing wastes containing hexachlorobenzene and to review and document methods currently used for treatment and disposal of HCB wastes.The chlorinated solvents and pesticide industries were found to account for nearly all HCB wastes produced (4,305 tons per year) by the 14 industries reviewed as sources of HCB wastes.Waste storage methods which are used prior to ultimate disposal include storage of solid waste cubes under plastic cover and use of water-covered lagoons. Methods for transportation of HCB wastes include use of forklift, truck, pipeline, heated tank trucks and rail. Ultimate waste disposal methods include land disposal, incineration (with or without by-product recovery), resource recovery, discharge to municipal sewage treatment plants, and emission to the atmosphere. The majority of the HCB waste handled by the industrial facilities reviewed is currently disposed of in two industrial landfills using a soil cover of 4 to 6 ft. with a polyethylene film placed at approximately the mid-depth of the soil cover. Incineration at a sufficiently elevated temperature can effectively destroy HCB; HCl can be recovered as a by-product.Very limited actual disposal cost data are available on existing facilities handling HCB wastes.     

基于收益分享合同的垃圾源头分类激励机制

通过建立两阶段的Stackelberg动态博弈模型,研究了固定不可燃垃圾处置费和变动垃圾处置费2种情况下,垃圾发电厂如何制订收益分享合同相关条款,促使居民实行垃圾源头分类,并提高可燃垃圾燃烧热值。结果表明:存在唯一的最优分享比例使得发电厂的收益最大,消费者的选择存在最优的可燃垃圾回收数量和最低垃圾燃烧热值水平。     

国内外生活垃圾焚烧发电技术进展

随着人们对环境方面要求的日益增长,垃圾合理处理在践行绿色发展理念和推动生态文明建设进程中发挥着越来越重要的作用。生活垃圾焚烧发电技术作为固废资源利用的一种方法,如今已经演变成为一种成熟的资源利用技术。分别从垃圾焚烧发电行业的上、中、下游,即从垃圾焚烧的原料性质、燃烧发电技术以及烟气控制方面对国内外生活垃圾焚烧技术进行了比较分析,认为随着生活垃圾量日益增长,生活垃圾焚烧技术仍是一种实现减量化、资源化必不可少的手段,但是需要提升焚烧技术,改进国产焚烧工艺,严格控制焚烧烟气中污染物的排放,建立实时监测点,避免造成二次污染。     

Breakthrough Technologies for the Biorefining of Organic Solid and Liquid Wastes

Organic solid and liquid wastes contain large amounts of energy, nutrients, and water, and should not be perceived as merely waste. Recycling, composting, and combustion of non-recyclables have been practiced for decades to capture the energy and values from municipal solid wastes. Treatment and disposal have been the primary management strategy for wastewater. As new technologies are emerging, alternative options for the utilization of both solid wastes and wastewater have become available. Considering the complexity of the chemical, physical, and biological properties of these wastes, multiple technologies may be required to maximize the energy and value recovery from the wastes. For this purpose, biorefining tends to be an appropriate approach to completely utilize the energy and value available in wastes. Research has demonstrated that non-recyclable waste materials and bio-solids can be converted into usable heat, electricity, fuel, and chemicals through a variety of processes, and the liquid waste streams have the potential to support crop and algae growth and provide other energy recovery and food production options. In this paper, we propose new biorefining schemes aimed at organic solid and liquid wastes from municipal sources, food and biological processing plants, and animal production facilities. Four new breakthrough technologies—namely, vacuum-assisted thermophilic anaerobic digestion, extended aquaponics, oily wastes to biodiesel via glycerolysis, and microwave-assisted thermochemical conversion—can be incorporated into the biorefining schemes, thereby enabling the complete utilization of those wastes for the production of chemicals, fertilizer, energy (biogas, syngas, biodiesel, and bio-oil), foods, and feeds, and resulting in clean water and a significant reduction in pollutant emissions.     

热害矿井空气能系统降温与废热提级利用系统设计

针对目前热害矿井在开采过程中存在的危害,各国针对存在热害的矿井采取了不同的防治措施,并且取得了一定效果,但是其系统的投资与运行费用较高。提出一种利用空气能系统对矿井进行降温的新模式,结合平顶山大庄矿矿井基本情况,对机电硐室进行空气能制冷降温与废热提级利用系统设计,并对主要设备进行了选型。最后与传统冷水机组制冷降温系统进行比较,空气能系统具有显著的经济效益。研究成果为企业节能减排方案的选择提供了参考和依据。     

Development of an inverse method to identify the kinetics of heavy metal release during waste incineration in fluidized bed

This paper deals with the emission of heavy metals (HM) during the incineration of municipal solid waste in a fluidized bed reactor. This study focused on the development of a general method to identify the kinetics of vaporization of heavy metals from the on-line analysis of exhaust gas. This method is an inverse method, which requires only the time evolution of the HM concentration in exhaust gases (experimental data) and a global bubbling bed model developed for transient conditions at the reactor scale. First, a lab-scale fluidized bed incinerator was set-up to simulate the HM release during the thermal treatment of metal-spiked model wastes. A specific on-line analysis system based on ICP-OES was developed to measure in real time the variation of the relative concentration of HM in exhaust gases. Then, a two-phase flow bubbling bed model was developed and validated to calculate the kinetics of vaporization of HM from its measured concentration time profile in the outlet gas. The technique was first validated with model waste (metal-spiked mineral matrices), thus enabling at each time both solid sampling for measuring the HM vaporization kinetic and on-line analysis for measuring the HM concentration in the outlet gas. The inverse method was then applied to realistic artificial wastes (derived from real wastes) to identify the HM vaporization kinetics from the on-line analysis results.     

Non-thermal plasma for oxidation of gaseous products originating from thermal treatment of wastes

A plasma reactor generating non-equilibrium plasma in a gliding discharge was applied as one of the modules of a new laboratory device for hazardous waste destruction. The degradation process of wastes containing an organic part was carried out in two stages. The first one consisted of thermal decomposition of wastes in an inert atmosphere (pyrolysis process in argon flow—the gaseous products are formed from the organic part of wastes). In the second stage products of pyrolysis were oxidized in a gliding discharge. This work was focused on study of the parameters influencing the oxidation process of gases originating from pyrolysis and flowing into the plasma reactor. Oxygen was introduced into the plasma reactor simultaneously with the gases. We investigated two factors significantly affecting the oxidation process: (a) the oxygen concentration in the initial mixture of argon and oxygen and (b) the total flow of argon and oxygen gases. The best oxidation efficiency of the processing gases in the plasma was reached when the oxygen content did not exceed 20% and when the total flow of argon and oxygen was low enough not to cause disturbances of functioning of the plasma reactor.     

High temperature corrosion of power boiler components cladded with nickel alloys

Incineration of biomass, waste and sorted rubbish in industrial boilers results in the formation of very aggressive chlorides and sulfur dioxides in off-gases. Harmful action of those substances and dusts in off-gases requires appropriate protection of certain boiler elements, such as heat exchanger pipes and the combustion chamber, against corrosion and erosion.The paper presents the results of attempts to perform pad welding of heat exchanger pipes with nickel alloys Inconel 625 and Inconel 686, and high-temperature resistance tests of the padded welds in an atmosphere of N₂ + 9% O₂ + 0.08% SO₂ + 0.15%HCl for 750 h.Corrosion processes induce the formation of a Cr₂O₃ oxide film of 5–10 μm thickness on the Inconel padded welds, which constitutes a passivation layer, reducing the corrosion rate. The presence of iron on the padded weld surface is conducive to the formation of Fe₃O₄ oxide, which worsens the padded welds' resistance to corrosion and erosion.It has been found that the pad welding technology developed and the padded weld properties of Inconel 625 and 686 comply with the requirements of standards and users, and therefore, it can be used for pad welding of components of boilers for waste utilization and biomass incineration.     

Solid waste generation from oil and gas industries in United Arab Emirates

Solid wastes generated from oil and gas industrial activities are very diverse in their characteristics, large in their amounts and many of which are hazardous in nature. Thus, quantifying and characterizing the generated amounts in association with their types, classes, sources, industrial activities, and their chemical and biological characteristics is an obvious mandate when evaluating the possible management practices. This paper discusses the types, amounts, generation units, and the factors related to solid waste generation from a major oil and gas field in the United Arab Emirates (Asab Field). The generated amounts are calculated based on a 1-year data collection survey and using a database software specially developed and customized for the current study. The average annual amount of total solid waste generated in the studied field is estimated at 4061 t. Such amount is found equivalent to 650 kg/capita, 0.37 kg/barrel oil, and 1.6 kg/m³ of extracted gas. The average annual amount of hazardous solid waste is estimated at 55 t and most of which (73%) is found to be generated from gas extraction-related activities. The majority of other industrial non-hazardous solid waste is generated from oil production-related activities (41%), The present analysis does also provide the estimated generation amounts per waste type and class, amounts of combustible, recyclable, and compostable wastes, and the amounts dumped in uncontrolled way as well as disposed into special hazardous landfill facilities. The results should help the decision makers in evaluating the best alternatives available to manage the solid wastes generated from the oil and gas industries.