WastetoEnergyPlantTechnology.pptx
- 2. Waste is a product or substance which is no longer suited for its intended use. Whereas in natural ecosystems waste (i.e. oxygen, carbon dioxide and dead organic matter) is used as food or a reactant, waste materials resulting from human activities are often highly resilient and take a long time to decompose. For legislators and governments, defining and classifying waste based on risks related to the environment and human health are therefore important in order to provide appropriate and effective waste management. For the producer or holder, assessing whether a material is waste or not is important in identifying whether waste rules should be followed. Definitions are also relevant in the collection and analysis of waste data as well as in domestic and international reporting obligations. Waste has been defined in most countries and is generally tied to the concept of disposal.
- 3. Wastes: Wastes are substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law. Forms of waste: Solid, Liquid, gases Solid waste (refuse): The wastes in the solid or semisolid forms are called solid wastes. Refuse comprises all of solid waste resulting from the normal activities of the community except excreta. Solid waste: Solid waste is all-inclusive, encompassing the heterogeneous mass of throw aways from the urban community as well as the more homogeneous accumulation of agricultural, industrial and mineral wastes.
- 4. Consequences of solid waste: 1. Littering of food and other solid waste in medieval towns-the practice of throwing wastes into the unpaved streets, roadways and vacant land led to the breeding of rats with their attendant fleas carrying bubonic plague. 2. The lack of any plans for the management of solid waste thus key to epidemic of plague, the Black Death. 3. Ecological phenomena such as water and air pollution have been attributed to improper management of solid waste. 4. For instance, liquid form dumps and poorly engineered landfills has contaminated surface waters and ground waters.
- 5. Methods for the final disposal of solid wastes: (i) Dumping on land (ii) Dumping in water (iii)Plowing into the soil (iv)Feeding to hogs (v) Reduction (vi) Incineration Objective of solid waste management The objective of solid waste management is to reduce the quantity of solid waste disposed off on land by recovery of materials and energy from solid waste. This in turn results in lesser requirement of raw material and energy as inputs for technological processes. Such techniques and management programs have to be applied to each and every solid waste generating activityin a society to achieve overall minimization of solid waste.
- 6. Effective management of solid waste Effective solid management systems are needed to ensure better human health and safety. They must be safe for workers and safeguard public health by preventing the spread of disease. In addition to these prerequisites, an effective system of solid waste management must be both environmentally and economically sustainable. Environmentally sustainable: It must reduce as much as possible, the environmental impacts of waste management. Economically sustainable: It must operate at a cost acceptable to community.
- 7. Waste management systems and their impact on environment
- 8. Waste can be classified based on source (who/what generated the waste? See Figure 1), substance (what is it made of?), hazard properties (how dangerous is it?), management (who handles it?) or a mix of these concepts.
- 9. Two main waste categories can be established based on the distinct legislation and policy instruments usually in place: non- hazardous or solid waste; and hazardous waste. Such a classification is also used in the Basel Convention. Hazardous waste is usually regulated at the national level, while non- hazardous is regulated at the regional or local (municipal) level. (See Figure 2.)
- 11. Non-hazardous/solid waste is all waste which has not been classified as hazardous: paper, plastics, glass, metal and beverage cans, organic waste etc. While not hazardous, solid waste can have serious environmental and health impact if left uncollected and untreated While a significant proportion of solid waste could theoretically be reused or recycled, collection by type of waste a prerequisite for reuse and recycling is one of the biggest waste management challenges. Hazardous waste is waste that has been identified as potentially causing harm to the environment and human health and therefore needs special, separate treatment and handling Chemical and physical characteristics determine the exact collection and recycling process. Flammability, corrosiveness, toxicity, ecotoxicity and explosiveness are the main characteristics of hazardous waste. Liquid, gaseous and powder waste need special treatment by default to avoid the dispersal of the waste. Generally, separate collection and handling are established to avoid contact with non-hazardous waste. Chemical treatment, incineration or high-temperature treatment, safe storage, recovery and recycling are possible modes of treatment for hazardous waste.
- 12. Most hazardous waste originates from industrial production. Special kinds of hazardous waste include: E-waste is waste from electric and electronic equipment such as end-of-life computers, phones and home appliances. E- waste is generally classified as hazardous because it contains toxic components (e.g. PCB and various metals). Medical waste originates from the human and animal healthcare systems and usually consists of medicines, chemicals, pharmaceuticals, bandages, used medical equipment, bodily fluids and body parts. Medical waste can be infectious, toxic or radioactive or contain bacteria and harmful microorganisms (including those that are drug-resistant). Radioactive waste contains radioactive materials. The management of radioactive waste differs significantly from that of other waste.
- 15. Waste to Energy(WTE) Waste energy works by burning waste at a very high tempr,heat is then transferred ,transformed into energy. the steam then drive a turbine-creates electricity and surplus heat which can be used for district heating and cooling. Also recovered clean water, valuable metals and construction material from the waste. Residual waste to energy is most economical compare to solar, tidal, wind, Hydro, Thermal and nuclear. According to the confederation of European waste to energy plants(CEWEP) Europe treats 50 million ton of waste at WTE plant, generates an amount of energy that can supply electricity for 27 million people and heat for 13 million people. Worldwide 130 million tonnes of MSW combusted annually in over 600 wte facilities that produce electricity & steam and recovered metals for recycling. 1ton MSW can generate up to 750 kWh. Ash 10% of original volume.
- 16. Apprx.100000MTonnes of waste is generated per day world wide, production of this waste is expected to be approximate 27 billion tonnes/year by 2050, 1/3 of this waste which will come from Asia( major countries China+ India) Waste generation rate in Urban India will become 0.7kg per person per day by 2025, 4-6 times higher than in 2012. Current-0.2-0.45kg/person/day on an avg. This waste has a potential of generating 439MW of power,1.3million cubic meter of biogas per day or 72 MW of electricity from Biogas and 5.4 million metric tonnes of Compost. Morover, 62 million tonnes annual generation of MSW requires 3,40,000 cubic meter of landfill space everyday (1240 hectare per year) if continues to be dumped.
- 17. Solid Waste Types Municipal solid waste commonly known as trash or garbage, refuse or rubbish is a waste type consisting of everyday items we consume and discard. It predominantly includes food wastes, yard wastes, containers and product packaging and other inorganic wastes from residential, commercial, Institutional and industrial sources. Organic waste –food scrapes, wood, rubber, canteen or cafeteria wastes, news papers, tires, furniture etc. Municipal solid waste does not include industrial wastes, agriculture waste and sewage sludge. Biodegradable waste-food and kitchen waste, green waste, paper (can be recycled); Recyclable material-Paper, glass bottles, cans, metals, certain plastics, etc.; Inert waste- dirt, rocks, debris, C & D waste Composite waste-waste plastics, tetra packs, waste closing
- 18. Waste to energy recovery plant waste-to-energy plant converts solid waste into electricity and/or heat - an ecological, cost-effective way of energy recovery. The energy plant works by burning waste at high temperatures(850) and using the heat to make steam. The steam then drives a turbine that creates electricity. .
- 20. Severe illnesses, including encephalitis and dengue fever, have been attributed to disease-carrying mosquitoes originating from scrap tire piles. Illegal dumping can impact proper drainage of runoff, making areas more susceptible to flooding when wastes block ravines, creeks, culverts, and drainage basins. In rural areas, open burning at dumpsites containing chemicals may contaminate wells and surface water used as sources of drinking water. Dumpsites that caught fire, either by spontaneous combustion or, more commonly. Rodents, insects, and other vermin attracted to open dumpsites may also pose health risks. The health risks associated with illegal dumping are significant for rag pickers and residents living nearby Areas used for illegal dumping may be easily accessible to people, especially children, who are vulnerable to the physical (protruding nails or sharp edges) and chemical (harmful fluids or dust) hazards posed by wastes. (Source: Illegal Dumping Prevention Guidebook. US EPA. EPA905-97-001)
- 21. 1. Segregation at source-Reduce, Reuse, Recycles, 2. Collection and transportation 3. Treatment and Energy Recovery-Waste which can be heated, converted processed into gas, fuel and electricity. 4. Scientific land filling for inert, hazardous and Toxic. Criteria for selection of WTE technology 1. Waste characterization-type ,quantity and waste content. 2. Environment and health-CO2 control, DXNs control, Emission control, landfill control.( Air, water and land pollution overall) 3. Economy-cost control, profit and growth, relative capital cost, O &M. 4. Energy and efficiency – energy recovery, high efficiency, utilization and safe. Power generation- Efficiency(50-60% based on VOC)
- 22. 3 E’s Technology selection Criteria Environment Economy Energy • Emissions control • Minimize Landfill Cost Vs. Benefit Social & Financial Energy recovery Efficiency Selection of waste to energy technology is based on scale of waste to be processed, existing emission norms, energy recovery and economic factors
- 23. Waste-to-Energy (WtE) also known as energy-from-waste, is complicated technology in the realm of renewable energy. The waste that is neither recycled nor used is converted to energy in the form of heat, steam or electricity. The electricity generated is fed into the grid and distributed to the households, industries, communities, etc. Hence, WtE provides a cost effective and hygienic alternative to treat residual waste, reducing its volume by 90% . WtE is an integral part to reach 100% RE in future along with other renewable sources.
- 24. Waste to energy recovery Stock pallet waste- furnaces-Burn- Heat-steam-Turbine-Electricity, Components: furnaces, turbines, heat exchanges boilers, generators etc. The technology options available for processing the Municipal Solid Waste(MSW)are based on either Bioconversion or thermal conversion The Bioconversion process is applicable to the organic fraction of wastes, to form compost or to generate biogas such as methane (waste to energy) residual sludge(manure). Various technologies are available for composting such as aerobic, anaerobic & vermi- composting. The thermal conversion technologies are incineration with or without heat recovery, pyrolysis and gasification, plasma pyrolysis and pelletization or production of Refuse Derived Fuel(RDF).
- 25. 1. Thermochemical Conversion of Waste The three principal methods of thermochemical conversion of MSW are combustion (in excess air), gasification (in reduced air), and pyrolysis (in absence of air). The most common technique for producing both heat and electrical energy from wastes is direct combustion. Combined heat and power (CHP) or cogeneration systems, ranging from small-scale technology to large grid-connected facilities, provide significantly higher efficiencies than systems that only generate electricity. Combustion technology is the controlled combustion of waste with the recovery of heat to produce steam which in turn produces power through steam turbines. Pyrolysis and gasification represent refined thermal treatment methods as alternatives to incineration and are characterized by the transformation of the waste into product gas as energy carrier for later co
- 26. 2. Biochemical Conversion of Waste Biochemical processes, like anaerobic digestion, can also produce clean energy in the form of biogas which can be converted to power and heat using a gas engine. Anaerobic digestion is the natural biological process which stabilizes organic waste in the absence of air and transforms it into biofertilizer and biogas. Anaerobic digestion is a reliable technology for the treatment of wet, organic waste. Organic waste from various sources is biochemically degraded in highly controlled, oxygen-free conditions circumstances resulting in the production of biogas which can be used to produce both electricity and heat.
- 27. 3. Physico-chemical Conversion of Waste The physico-chemical technology involves various processes to improve physical and chemical properties of solid waste. The combustible fraction of the waste is converted into high-energy fuel pellets which may be used in steam generation. The waste is first dried to bring down the high moisture levels. Sand, grit, and other incombustible matter are then mechanically separated before the waste is compacted and converted into pellets or RDF. Fuel pellets have several distinct advantages over coal and wood because it is cleaner, free from incombustibles, has lower ash and moisture contents, is of uniform size, cost-effective, and eco-friendly.
- 29. Technologies for conversion of WtE Waste to energy technologies recover energy from organic fraction of waste using either biochemical or thermo chemical processes Waste Thermo chemical Biochemical Crushing, compressing, pelletizing Incineration Conventional/ Plasma gasification Pyrolysis Biomethanation Fermentation Refuse derived fuel Flue gas/steam Syngas Syngas & Bio-oil Biogas Ethanol Mechanical Electricity Chemicals Hydrogen Transport fuel Feed stock for thermal process Heat Concept Process Energy carrier Application
- 31. Incineration • Incineration involves combustion of waste at very high temperatures in the presence of excess oxygen • Results in the production of ash, flue gas and heat energy • Incineration is feasible for unprocessed or minimum processed refuse besides for the segregated fraction of the high calorific waste Advantages • Immediate reduction in volume and weight by about 90% and 75% respectively • Stabilization of waste • Energy recovery Challenges • Management of dioxins and furans formed in incineration Incineration is a maturated technology for processing and energy recovery from waste
- 32. Organic matter + excess air N2 + CO2 + H2O + O2 + ash + heat
- 34. Gasification • Gasification is thermo chemical conversion of carbonaceous fraction of waste into syngas (CO, H , 2 CH4 and CO ) 2 in oxygen deficient environment and at high temperatures (650- 1600°C) • Inorganic fractions present in the waste converted to ash and can be safely land filled • Syngas can be used for variety of applications such as generation chemicals, hydrogen electricity, Bio fuels, Advantages • Immediate reduction in volume and weight • Environment friendly • Energy efficient Challenges • Higher initial cost compared to incineration • Skilled labour is required Gasification is more efficient and environmental friendly technology than incineration for conversion waste into energy
- 36. Plasma gasification • Plasma is an ionized gas where the atoms of the gas have lost one or more electrons and have become electrically charged • Waste introduced into the plasma field, where intense heat breaks down the waste molecules into simple compounds • Waste converted into fuel gases with high calorific value and inert solid slag in the temperature range 1200 – 2000 C 0 Advantages • Immediate reduction in volume and weight • Converts waste to inert vitrified slag • Suitable for low calorific value waste Challenges • Expensive compared to conventional gasification • Skilled labor is required Plasma gasification is an emerging waste to energy technology for processing of variety of waste such as MSW, medical waste, agro waste etc.
- 37. Pyrolysis • Pyrolysis is thermal decomposition of organic fraction of waste in the absence of oxygen • Pyrolysis is an endothermic process and usually required heat is generated by burning of some of the product gas in separate heater • Pyrolysis produces three components: Fuel gas: A mixture of fuel gases Fuel oil: Consisting of tar, pitch, light oil etc. Char along with the inert materials in the waste feed Advantages • Immediate reduction in volume and weight & less space requirement • Stabilization of waste • Easy to operate Challenges • Pyrolysis oil is unstable & needs further processing • Energy is distributed in 3 fractions Pyrolysis of waste plastics is an upcoming technology for conversion plastics to either liquid fuels or chemicals
- 38. Hydrolysis and fermentation • First step in conversion of cellulosic fractions of waste to ethanol is hydrolysis of cellulose and hemicellulose into simple sugars using chemicals / enzymes • Second step is fermentation of sugars into ethanol followed by distillation • Lignin is by a product in this process Advantages • Generation of drop-in bio-fuels • Stabilization of waste • Energy recovery Challenges • High capital and O & M Cost • Convert only cellulosicand hemi cellulosic fractions • Conversion of polysaccharides to sugars is complex Major challenges in hydrolysis and fermentation are integration of hydrolysis and fermentation into single step, and availability of low cost enzymes –Biochemical process
- 39. Besides the individual processes (incineration, gasification or pyrolysis), combinations of these processes, possibly combined with other processes (e.g. melting, distillation) are also applied. A limited selection of combination processes is presented in the following subsections. Combination pyrolysis – gasification Combination gasification – combustion
- 40. Refuse Derived Fuel(RDF) • RDF is produced by removing recyclables and noncombustibles from waste and producing a combustible material by shredding, compressing and pelletization of remaining waste • RDF is easily storable, transportable, and more homogeneous fuel for either steam/ electricity furnaces/boilers generation or as alternate fuel in industrial • RDF may also be utilized in co-processing in cement kilns, co-combustion in coal fired power plants Advantages • High calorific value of the waste Challenges • Suitable for the areas where large amount of combustible waste is being generated
- 41. RDF process flow scheme RDF is usually prepared in the form of pellet/ briquette/ fluff from dry high calorific value combustible wastes
- 42. Typical reaction conditions and products from pyrolysis, gasification and incineration processes
- 44. Handling and storage of waste: Refuse Bunkers, pallets, moving cranes, storage units, blown air curtains to prevent odor outside. Waste incineration: Furnace, fire grates, air blowers, Boilers with HE and Air condensers, closed loop of water supply feeding station. Flue gas treatment unit: Gas cooler, gas scrubber, electrostatic precipitator, bag filters, addition of lime and activated carbon process, DeNOx reactor, emission control for residue(APCR) Fly ash Chamber and Bottom ash chamber: Steam Turbine : low pressure high speed turbines, generators, electricity tower etc. District heating system: part of steam used for community heating. Leachte treatment unit: waste water and wet flue gas treatment. Magnetic tray: On the bottom of furnace, recycled metals, vitrified glass and other metals
- 48. Renewable resource Reduces landfills- volume reduction by 90% only residue goes to landfill Protects clean water supplies Reduces air pollution and smog-advanced pollution control of gas emissions and flue gases. Reduces ground and surface water pollution Reduces greenhouse gases ◦ Carbon dioxide ◦ Methane
- 49. THANK YOU FOR YOUR KIND ATTENTION !!
- 50. Trend of Resource Circulation Policy
- 51. Strategy of Waste Resource & Biomass Energy
- 52. Energy Recovery Equation
- 53. Attributes Incineratio n RDF Anaerobic digestion Pyrolysis Gasification Landfill gas Methods Thermoche m ical Thermochemical Biochemical Thermochemi cal Thermochemical Biochemical Suitable waste characteristics Sorted combustible waste Sorted combustible waste Sorted organic waste: suitable for either wet or dry waste depending on type of AD system Sorted heterogeneous MSW Sorted organic (combustible, putrescible, and plastic fractions of the waste) Unsorted waste Description Waste is broken down to produce heat. Waste is broken down to produce the high calorific fraction. Organic biodegradable waste broken down without oxygen (anaerobic) to produce methane gas, carbon dioxide, water, and digestive (which is composted). Can be wet or dry. Waste is broken down by heat in the absence of oxygen to produce fuel gas. Waste is broken down by heat with a limited quantity of oxygen to produce fuel gas. Waste placed in a landfill breaks down over time due to biological, physical, and chemical processes emerging technologies, such as bioreactor landfills, may offer more sustainable approaches to landfill disposal of wastes. Energy form Heat Solid fuel Fuel gas Char, pyrolysis oil, and gases Syngas LFG General performance Thermal treatment can divert 70 per cent of waste from landfill Can divert most combustible of waste from landfill Can divert all or most organic and biodegradable products (food, yard waste, some papers) Can divert most a mixed (heterogeneou s) waste stream from landfill Can divert most combustible organic of waste from landfill A wide range of performance is available. Individual facilities are custom designed and constructed to meet desired waste management objectives COMPARISON OF DIFFERENT TYPES OF WTE TECHNOLOGY.
- 54. Community characteristics Thermal treatment is a high-tech system that requires skilled technical operators. Depending upon the specific technology, it is suitable for communities ranging from small villages to large urban RDF systems treat waste is a high-tech system that requires skilled technical operators. Depending upon the specific technology, it is suitable for communities ranging from large urban Anaerobic digestion is a high-tech system that requires skilled technical operators. It is most suited to reasonably large urban areas to justify the construction of the system Pyrolysis of waste is a high-tech system that requires skilled technical operators. Depending upon the specific technology, it is suitable for communities ranging from large urban Gasification of waste is a high-tech system that requires skilled technical operators. Depending upon the specific technology, it is suitable for communities ranging from large urban Landfill disposal of waste is a necessary element of an integrated approach to waste management in all Thailand communities Factors that influenced acquisition The availability of local energy markets is a critical factor in the decision The availability of local energy markets is a critical factor in the decision Availability of local energy The availability of local energy markets is a critical factor in the decision The availability of local energy markets is a critical factor in the decision Low costs relative to other options. Limitations on availability of other alternatives Possible environmental impact air pollution, particulate matter, solid residue and wastewater soot or dust and air pollution generated from fuel burning odor and disease generated from solid wastes fermentation gas or vapor from combustion, carbon black, solid residue from burning and wastewater gas or vapor from combustion, carbon black, solid residue from burning and wastewater Methane gas that is risk to explosion Energy implication Thermal energy and convert to electrical energy Thermal energy and convert to electrical energy Net energy generator Energy for conventional engines and boilers Energy for making products; Methanol, Ammonia, Diesel fuel Net energy generator
- 55. Waste to Energy Fundamentals There are three principal ways to recover the energy content of MSW by treating it thermally, as shown below. These include pyrolysis, gasification and combustion. These processes are differentiated by the ratio of oxygen supplied to the thermal process divided by oxygen required for complete combustion. This ratio is defined as the “lambda” ratio and in the case of pyrolysis, it is equal to zero. Gasification is conducted at substoichiometric conditions and full combustion is carried out using a lambda greater than one. • Pyrolysis λ= 0, no air, all external heat • Gasification λ = 0.5, partial use of external heat • Combustion λ = 1.5 +, no external heat where λ represents: oxygen input/ oxygen
- 59. The waste is recovered if: • Its combustion generates more energy than is consumed by the process itself; • Most of the waste is consumed during the operation • Most of the energy generated is recovered and used ( either as heat or electricity) • The waste replaces the use of a source of Primary Energy
- 60. A designated calculation procedure takes the amount of useful electricity and heat DESIGNED to be produced by the facility and applies appropriate factors to determine the amount of energy necessary to produce this with modern plant. It then compares this energy requirement with the energy used by the facility. This approach uses a complicated set of data including: • Start-up oil, • Standby power, • Imported power, • Energy required to run the plant and • Energy required for dust removal and gas clean up. If the factor produced is < 0.65 the facility is classed DISPOSAL. If the factor produced is =>0.65 the facility is classed RECOVERY.
- 61. The definition of energy efficiency used in the revised WFD is: where: Ep means annual energy produced as heat or electricity. It is calculated with energy in the form of electricity being multiplied by 2.6 and heat produced for commercial use multiplied by 1.1 Ef means annual energy input to the system from fuels contributing to the production of steam Ew means annual energy contained in the treated waste calculated using the lower calorific value of the waste Ei means annual energy imported excluding Ew and Ef 0.97 is a factor accounting for energy losses due to bottom ash and radiation. Comparison With Other Generating Methods • Coal Fired Power station: 37% efficient • Gas Fired CCGT: 41% efficient • Waste Fired Power Station (EfW) 26% Efficient
- 62. Calculate the Energy Content of MSW Total Energy = (Solid waste, lb) * (Energy Content, Btu/lb) Specific Energy content = Total energy Btu Total waste,lb
- 64. Electricity output= LHV*Waste flow*Electrical efficiency where LHV: MJ/kg, Waste flow: kg/d or yearly bas