Search results

Cement production has advanced greatly in the last few decades. The traditional fuels used in traditional kilns include coal, oil, petroleum coke, and natural gas. Energy costs and environmental concerns have encouraged cement companies worldwide to evaluate to what extent conventional fuels can be replaced by waste materials, such as waste oils, mixtures of non-recycled plastics and paper, used tires, biomass wastes, and even wastewater sludge. The paper aims to discuss these issues.

The work is based on literature review.

The clinker firing process is well suited for various alternative fuels (AF); the goal is to optimize process control and alternative fuel consumption while maintaining clinker product quality. The potential is enormous since the global cement industry produces about 3.5 billion tons that consume nearly 350 million tons of coal-equivalent fossil and AF. This study has shown that several cement plants have replaced part of the fossil fuel used by AF, such waste recovered fuels. Many years of industrial experience have shown that the use of wastes as AF by cement plants is both ecologically and economically justified.

The substitution of fossil fuels by AF in the production of cement clinker is of great importance both for cement producers and for society because it conserves fossil fuel reserves and, in the case of biogenic wastes, reduces greenhouse gas emissions. In addition, the use of AF can help to reduce the costs of cement production.

The purpose of this paper is to determine the production and energy potential of refuse derived fuel (RDF) in Latvia, in order to understand how large an impact municipal waste incineration with energy recovery has on waste management and energy supply systems in Latvia.

The results of the study are based on historical data of municipal solid waste (MSW) management. The potential of RDF in Latvia is estimated and future sources of RDF production until 2020 are projected. The calculations of RDF potential are based on data on MSW generation, landfilling and composition, and on the calorific value of RDF fractions. The study also takes into account experimental results of RDF production trials in one landfill in Latvia.

The amount of MSW landfilled annually until 2020 will grow, therefore new waste management options will have to be found in order to comply with EU waste policy. One of the options is waste‐to‐energy. The energy amount potentially produced by incinerating RDF made of MSW in Latvia could account for approximately 2 per cent of the total energy amount produced in 2010, if the RDF conversion rate is assumed to be 30per cent, and up to 3.5 per cent – if the RDF conversion rate is 50 per cent.

There are just a few studies analysing RDF potential for a certain region (in this case – country). There is a lack of data and official projections of generated waste amounts which are typical for Latvia, therefore no detailed assessments are available on how much energy it would be possible to produce from the waste generated in Latvia. In this paper, the RDF production potential itself, as well as the energy potential produced via RDF in Latvia, is assessed. In order to estimate future availability of resources for RDF production, future MSW generation and landfilling amounts in Latvia until 2020 are projected.

The purpose of this paper is to present a three‐dimensional CFD model that simulates the pyrolysis, combustion and heat transfer phenomena in a refuse‐derived fuel (RDF) gasifier. Correlations between different operation conditions and the waste stack morphology are also investigated. Parametric studies are conducted to optimize operating conditions to achieve an even stack surface minimal the local oxidation in the waste stack.

This paper proposes a Lagrangian pyrolysis submodel which can be applied to determine the local pyrolysis rate and porosity field by introducing the local characteristic diameter of the waste solid sphere. The flow field is described by a single‐phase porous flow model using the SIMPLE algorithm with momentum extrapolation. A one‐step global reaction was adapted for the chemical reactions inside the gasifier.

Computational results produced three‐dimensional distribution of the flow field, temperature, species concentration, porosity and the morphology of the waste stack under different operation conditions. Some parametric studies were conducted to assess the effects of the inlet temperature and the feeding rate on the waste stack shape. The results demonstrated that the model can properly capture the essential physical and chemical processes in the gasifier and thus can be used as a predictive simulation tool.

Due to the lack of accurate reaction rate information, the computational results have not been directly compared against experimental data. Additional refinement and subsequent validation against prototype gasifier experiment will be reported in future work.

A full three‐dimensional computational model is developed for the complex two‐phase flow based on porous medium representation of the solid stack. A Lagrangian pyrolysis model based on the characteristic diameter of the solid waste material was proposed to describe the pyrolysis rate history. The developed model reproduces correct physical and chemical behavior inside gasifier with adequate computational efficiency and accuracy.

In a new build waste incinerator, the waste (refuse derived fuel) was burned on a discontinuous moving grate. Frequent furnace overpressure peaks occurred because of this firing method and as a result, flue gas and fly‐ash were pushed out of the boiler and into the building. During the plant start up period, a seal in a water‐feed pipeline broke, and a large amount of condensed steam was discharged into the boiler house. Shortly thereafter, very severe corrosion was noticed on the galvanised gangways, steel building components, the boiler aluminium sheeting and on processing lines. A theoretical study of the condensation of the flue gas indicated that sulphuric acid would condense before it reached the external aluminium sheeting and that under normal conditions, dry hydrochloric acid fumes would be removed by the boiler house ventilators. However, the steam leakage had caused the hydrochloric acid to be dissolved in the condensed water and that had resulted in the severe corrosion damage, which had become evident subsequently.

This paper seeks to focus on energy recovery from municipal solid waste (MSW) in Croatia. The state strategy is based on the mechanical and biological treatment of waste in the future waste management centers (WMC). Left over after the treatment is waste that can be used as fuel (e.g. RDF).

Starting from the geographical distribution of waste generation (quantities and transport distances), taking into account the costs of collection, transfer and thermal treatment, recommendations on optimal number and size of the dedicated waste‐to‐energy (WtE) plants in Croatia as well as their potential locations are given. The opportunity of the cement industry to utilize ash from thermal treatment of waste in the process of the cement production and the RDF as a substitute fuel is also examined.

By varying the number of WMCs, the minimal specific cost of waste collection of €33 is obtained, for maximal number of WMCs, which is 21. The optimal capacity of WtE facility is approximately 300,000 t/year, for expected quantity of 600,000 t/year of waste available for energy recovery. However, the geographical shape of Croatia and traffic connections suggest that its area could be better covered by four WtE facilities, each with the capacity of 150,000 t/year. The alternative solution could include the existing cement industry. In this case one bigger WtE plant (preferably near the city of Zagreb) could be built, with the capacity of 400,000 t/year, while the rest of the waste would be used in the cement industry, which capacity amounts to 167,000 tons of RDF annually.

This analysis gives another view of a possible system for energy recovery from MSW in Croatia. MSW has never been used in Croatia for the purpose of energy generation on a wider scale.

In 1987, Campbell Soup Company introduced the Souper Combo, a line of frozen soup and sandwiches. Melvin Druin, vice‐president for packaging, called it “the perfect combination of old‐fashioned good taste and today's convenience. No mess. No fuss. Easy to use. All you have to do is clean your spoon. Everything else just throw away.” Unfortunately, the multi‐layered plastic‐coated packaging does not just disappear when thrown away. Plastics packaging, particularly from convenience products, has become a waste disposal nightmare. Garbage, an environmental magazine, gave the Souper Combo an “in the dumpster” award, saying, “It's precisely the kind of product that's created the municipal landfill monster.”

The purpose of the article is to identify relevant criteria for decision support in the implementation of waste-to-energy (WtE)-based systems.

The methodology is a simple case study with a qualitative approach. Five experts involved in the project of a thermoelectric power plant qualitatively evaluated, on a Likert scale, a decision model with 15 indicators derived from recent studies. The research object was the first stage of a project to implement a thermoelectric plant employing municipal solid waste (MSW) in southern Brazil.

The study identified 15 criteria supporting the decision-making process regarding WtE implementation for MSW in a mid-sized city in southern Brazil. The study identified that compliance with MSW legislation, compliance with energy legislation, initial investment and public health impact are the most influential criteria. The study offered two models for decision processes: a simplified one and a complete one, with ten and fifteen indicators, respectively.

The study concerns mid-sized municipalities in southern Brazil.

Municipal public managers have now a methodology based on qualitative evaluation that admits multiple perspectives, such as technical, economic, environmental and social, to support decision-making processes on WtE technologies for MSW.

MSW management initiatives can yield jobs and revenues for vulnerable populations and provide a correct destination for MSW, mainly in developing countries.

The main originality is that now municipal public decision-makers have a structured model based on four constructs (technical, economic, environmental and social) deployed in 15 indicators to support decision-making processes involving WtE and MSW management.

The production, distribution and disposal of packaging materials consumes vast amounts of energy. These costs are quantified and ways in which they can be reduced are described. Recycling of materials is seen as offering distinct environmental advantages in terms of energy saving as part of an overall strategy, together with the use of more efficient forms of transport. The development of other forms of energy to replace environmentally harmful fossil fuels is seen as necessary.

The purpose of this paper is to examine a greenhouse gas (GHG) emission reduction potential from different waste management practices in Croatia. Energetic, environmental and economic benefits can be accomplished by utilizing municipal solid waste (MSW) and landfill gas as fuel in industry and energy sector, which is emphasized in this paper. The paper gives an overview of measures for energy recovery from MSW and landfill gas that could be implemented in Croatia. These measures also represent measures for an additional GHG emission reduction by decreased use of fossil fuels.

A methodology used for emission calculation (kinetic model) is explained. Three different scenarios of GHG reduction in waste management were defined. Implementation of best available techniques in waste management is envisaged by cross‐sectoral impact and effect of respective measures. Findings –This paper gives maximum achievable potential of GHG emission reduction with defined measure implementation dynamics. It was calculated that around one million ton of CO₂ can be avoided in 2020, which is 2.7 percent of projected GHG emissions in Croatia. The energy that could be recovered from waste (8.34 PJ in 2020) is relatively small in relation to the total final energy consumption in Croatia (about 3 percent).

The novelty of this work is achieved through integrated approach to GHG emission reduction and energy potential from MSW management in Croatia. The GHG reduction potentials are calculated by taking into account dependencies and interactions between the measures.

Polyvinyl chloride (PVC) in its many forms accounts for a large proportion of plastics production and packaging in Western Europe. Its applications and fitness for purpose as a food packaging are outlined, together with an analysis of the energy and materials required and by‐products made in its production. Methods of production are outlined, noting the environmental and health hazards. Problems associated with its disposal are described.