Dangkor is the main landfill site, receiving approximately , tonnes of waste per year. A rough estimate suggests that about 59, tonnes of greenhouse gases are emitted from the landfill each year. This initiative is coordinated by the environment, economy and interior ministries and municipalities. Each sub-national authority is given decision-making power for contracting with private waste collecting companies. Given this initiative, in November a new sub-decree on urban garbage and solid waste management was introduced.
It aims to strengthen and delegate the responsibilities of sub-national government on managing garbage and wastes in their municipalities. It details the responsibilities of concerned authorities including Ministry of Environment, Ministry of Interior and sub-national governing bodies.
This sub-decree does not cover industrial and hazardous wastes. At the same time, Leng Vy, an under-secretary at the Interior Ministry, said that the ministry was preparing information about waste management for the general public. The organic and plastic wastes are mixed. Raising public awareness of the benefits of separating wastes is a significant challenge for the Kingdom.
Studies say Cambodia has almost no recycling infrastructure. Some of its recyclable waste goes to Thailand and Vietnam for reprocessing. The temperature of the product gases is the flame temperature of interest 10 , 11 , 27 often termed T exit , T 2 or T f.
The typical value of c p 10 can be used to make fairly accurate estimate of the theoretical flame temperature and the final temperature of the gases after adding excess air. Actual flame temperatures are always lower than the adiabatic theoretical flame temperature since there is always a substantial quantity of heat released to the environment. Since the heat release per unit mass of fuel burned Q 1 , is known as a function of temperature, the heat balance becomes. Note that the heat released from combustion is the lower heating value LHV , because the moisture content is not condensed in order to absorb the latent heat of condensation.
At this stage, during design there is need to simultaneously determine the flame temperature and the value of Q 1. The evaluation of these quantities require the knowledge of the interchange of energy between an isothermal black enclosure with area and a gray gas flame filling the enclosure.
The rate of energy radiation by the flame q rad is given by:. However, the wall, at absolute temperature T c , will also radiate energy and a portion of this will be absorbed by the gas. The rate of energy absorption by the gas is obtained from:.
Now considering the net rate of interchange between the entire volume of gas and a portion of the enclosure e. To extend this concept to more realistic case of the combustion chamber lined with non-black, cold tubes which absorb radiation and a refractory that reradiates all the radiation which fall on it.
Equation 30 still gives the interchange between the flame and area A c , which now is the effective area but must be re-evaluated to include effect of the refractory and the emissivity of area A c. Since the refractory reradiates all the radiation it receives, its emissivity does not enter into the calculation.
The total rate of heat transfer from the flame in the boiler region, q, is the sum of the radiative heat transfer plus convective heat transfer. In most cases the convective heat transfer is only a small fraction of the radiation heat transfer in the combustion chamber and is often neglected.
Assuming sufficient turbulence so that exit gas temperature and average flame temperature are equal and the absolute temperature of the absorber is less than one-half the flame temperature, the radiation from the cold surface is not a major factor and use of a single emissivity is allowable.
Incinerator design cannot be effected without the knowledge of the basic combustion science, engineering and the characteristics of the waste. In order not to alter the authenticity of some tables from the literature; they are reported as they are with their original units. This work is licensed under a Creative Commons Attribution 4.
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Sustainable Energy. Oumarou, M. Sustainable Energy , 6 1 , Research Article. Open Access Peer-reviewed. DOI: Toggle navigation. Abstract The paper presents some basics and the steps required when the design of an incinerator for heat recovery or waste treatment is being thought of. Keywords: municipal solid waste incineration design heating value air fuel ratio waste management. Introduction Amidst various waste treatment methods like recycling, composting; incineration is the method that treats the non-reusable and non-organic portion of wastes.
Incineration Mechanisms and Their Selection 2. Typical grate firing systems for refuse incineration are shown in Figure 1: i. Reciprocating grates, ii. Roller grates and, iii. Reversed feed grates. Furnace Geometries Furnace geometry is one of the main features to influence and to optimize the primary combustion. Three 3 standard geometries for municipal waste incineration plants have been established and used worldwide as shown in Figure 2: a Parallel flow, b Counter flow and, c Centre flow.
Secondary Air Injection By dividing the total combustion air having an over-stoichiometry of 1. Download as. Figures index. Figure 1. Grate types schematic for municipal waste incineration plants [9]. Figure 2. Furnace geometries schematic for municipal waste incineration plants [9]. Table 1. Advantages and disadvantages of the different furnace geometries [9].
PowerPoint Slide. Tables index. Full Size Next Table. Figure 3. Different secondary air injection concepts in municipal wastes incineration [9]. Factors Affecting Incineration A good combustion process depends on the waste repartition on the grate, the effectiveness of the waste mixing to allow for a good contact between the combustible and air, a sufficient temperature in the drying-pyrolysis zone primary air pre-heating and intense radiation as well as a sufficient post combustion chamber temperature.
Heating Value or Calorific Value The calorific value of refuse fuel is a complex function of the elemental composition of the refuse. Theoretical Air to Fuel Ratio The oxygen for the combustion process comes from the air supplied to the burners. Fuel is mostly burned in the oxygen from air. Excess Air Requirement When incinerating refuse or fuel is being oxidized, some minimum air is stoichiometrically required for combustion. The percentage excess air is defined as: 10 P-excess air. Table 2.
Typical excess air values for various incinerator types [10]. Table 3. Preliminary design factors of MSW incinerators [13]. Table 4. Typical Heat release Rates of various incinerator systems [10].
Table 5. Supplementary Fuel Combustion characteristics [10]. Table 6. Residence times in the after-burning zone as a function of the temperature [9]. Full Size Previous Table. Basic Flame Kinetics and Heat Transfer 5. Estimation of Fuel Requirements The fuel requirements are known from knowledge of the total steam requirements and the heat released in the furnace per unit mass of fuel. It is achieved by solving the heat balance around the entire furnace 25 : 20 21 where: In most instances, preheating of the air is done within the furnace 26 , the air enters the furnace at room temperature and its enthalpy is negligible, thereby eliminating the term.
Theoretical Flame Temperature The heat released by combustion Q raises the temperature of the flow stream W of the products of combustion. Actual Flame Temperature Actual flame temperatures are always lower than the adiabatic theoretical flame temperature since there is always a substantial quantity of heat released to the environment.
The rate of energy radiation by the flame q rad is given by: 27 However, the wall, at absolute temperature T c , will also radiate energy and a portion of this will be absorbed by the gas. The rate of energy absorption by the gas is obtained from: 28 The net rate of radiation interchange between the gas and the black enclosure is then 29 Now considering the net rate of interchange between the entire volume of gas and a portion of the enclosure e.
Conclusion Incinerator design cannot be effected without the knowledge of the basic combustion science, engineering and the characteristics of the waste. Note In order not to alter the authenticity of some tables from the literature; they are reported as they are with their original units. Pamphlet, June The History of Refuse Derived Fuels.
Resources and Conservation. Elsevier Science Publishers, Amsterdam, Netherlands, Pijnenborg and Marcus A. Types of Incineration based on Technological Features. Waste Prevention Association, Greenpeace International publication, New grate-based waste-to-energy system produces inert ash granulates.
Waste management World, pp: , May-June Waste Incineration Handbook; U. Modern Power Plant Engineering. Paul and Richard A. Young Pollution Engineering practice Handbook.
Ann Arbor Science publishers Inc. Engineering Design: Incinerators Mobilization Construction. Lee; Huffman G. Basic Combustion and Incineration. Mc Graw-Hill, Transactions of the institution of Chemical Engineering , 78 part B, An Introduction to Coal Technology.
Academic Press New York, Process control in municipal solid waste incinerators. Waste Management and Research, 22 3 : , Handbook of incinerator Systems. McGraw-Hill, New York, Fuzzy Control in waste incineration plants; experiences in several types of plants. June Power Station Engineering and Economy. Mc Graw-Hill; New York, Waste-to-Energy in the United States. Numerical Calculation and Optimization of a large Municipal Waste incinerator plant.
Allyn and Bacon, Boston, Safe Management of wastes from health-care activities. World Health Organization-Geneva, Planning Fundamentals of Thermal Power Plants. Power Engineering, pp: , February Chemical Engineers Handbook. In article. Like this article. Sections Figures Tables References Abstract 1. Introduction 2. Incineration Mechanisms and Their Selection 3. Factors Affecting Incineration 4. Mass and Energy Balances 5. Basic Flame Kinetics and Heat Transfer 6. Conclusion Note References.
View in article. Full Size Figure. Full Size. Harvey Alter. Yongxiang Yang, Marc J. Gluszynski Pawel. Swithenbank J. Gohlke Oliver, Sri M.
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