Q: What happens inside a modern waste-to-energy facility?
A: The energy value of municipal solid waste (MSW) can be recovered through waste-to-energy incineration. Modern energy recovery facilities burn MSW in special combustion chambers, then use the resulting heat energy to generate steam or electricity. This process reduces the volume of MSW to be landfilled by as much as 90 percent.
Energy recovery facilities are designed to achieve high combustion temperatures, which help MSW burn cleaner and create less ash for disposal. Modern air pollution control devices - electrostatic precipitators, dry and wet scrubbers, and/or fabric filters - are used to remove potentially harmful particulates and gases from incinerator emissions.
Q: Is waste-to-energy incineration safe?
A: Yes. In 1989, the U.S. Conference of Mayors convened an international blue-ribbon panel of experts to discuss the health and safety impacts of waste-to-energy incineration. The symposium participants concluded that a properly equipped, operated and maintained energy recovery facility can operate within existing regulatory standards for human health and safety. The Clean Air Act of 1991 provided for an additional margin of security with tightened emissions standards. Furthermore, many communities are recognizing the importance of removing recyclables, as well as items such as batteries and household hazardous wastes, before incineration to reduce toxic components in incinerator ash.
The symposium participants found that, contrary to popular misconception, there is no evidence to link the incineration of PVC with increased dioxin emissions. Similar conclusions have been reached in a number of sources, including a 1987 study for the New York State Energy Research and Development Authority. Generally speaking, electricity is generated as safely through waste-to-energy incineration as it is through a power plant.
Q: How much waste-to-energy capacity is there?
A: There are 121 energy recovery facilities operating in the United States, with a designed capacity of nearly 97,000 tons per day. An additional five facilities are under construction and 31 are in the planning stages. If all of these facilities come on line as planned, 19 percent of the nation's MSW will be processed by energy recovery facilities by the year 2000.
Q: How do plastics contribute to waste-to-energy incineration?
A: Plastics are derived from petroleum or natural gas, giving them a stored energy value higher than any other material commonly found in the waste stream. In fact, one pound of plastics can generate twice as much energy as Wyoming coal and almost as much energy as fuel oil. When plastics are processed in modern waste-to-energy facilities, they can help other waste combust more completely, leaving less ash for disposal in landfills.
Energy Values
Material Btu/pound
Plastics
PET 10,900
HDPE 18,700
Other Plastic Containers 16,400
Other Plastics 17,900
Rubber & Leather 12,800
Newspaper 8,000
Corrugated Boxes (paper) 7,000
Textiles 9,400
Wood 7,300
Average for MSW 5,900
Yard Wastes 2,900
Food Wastes 2,900
Heat Content of Common Fuels
Fuel Oil 20,900
Wyoming Coal 9,600
Courtesy: SPI
Showing posts with label Plastic Waste Management. Show all posts
Showing posts with label Plastic Waste Management. Show all posts
Sunday, September 12, 2010
Tuesday, September 7, 2010
Conversion of Plastics waste into Liquid Fuel
A research-cum-demonstration plant was set up at Nagpur, Maharashtra for conversion of waste plastics into liquid fuel. The process adopted is based on random de-polymerization of waste plastics into liquid fuel
in presence of a catalyst. The entire process is undertaken in closed reactor vessel followed by condensation, if required. Waste plastics while heating upto 2700 C to 3000 C convert into liquid-vapour state, which is
collected in condensation chamber in the form of liquid fuel while the tarry liquid waste is topped-down from the heating reactor vessel. The organic gas is generated which is vented due to lack of storage facility. However, the gas can be used in dual fuel diesel-generator set for generation of electricity. The process includes the steps shown ahead:
Environment related observations during the process
❯ There are no liquid industrial effluents and no floor washings as it is a dry process.
❯ There are no organized stack and process emissions.
❯ Odour of volatile organics has been experienced in the processing area due to some leakages or lack of proper sealing
❯ Absolute conversion of liquid-vapour was not possible into liquid, some portion of gas (about 20%) is connected to the generator. However, the process will be improved in full-scale plant.
❯ PVC plastics waste is not used and if used, it was less than 1%. In case PVC is used, the chlorine can be converted into hydrochloric acid as a by-product.
❯ The charcoal (charcoal is formed due to tapping of tarry waste) generated during the process has been analysed and contain heavy metals, poly aromatic hydrocarbon (PAH) which appears to be hazardous in nature. The source of metals in charcoal could be due to the presence of additives in plastics and due to multilayer and laminated plastics.
❯ Monitoring of process fugitive emissions in the work area as well as emissions from the engines/diesel generator sets is necessarily required (where this liquid fuel is used) for various parameters such as CO, HCl,
Styrene, Benzene, VOCs.
in presence of a catalyst. The entire process is undertaken in closed reactor vessel followed by condensation, if required. Waste plastics while heating upto 2700 C to 3000 C convert into liquid-vapour state, which is
collected in condensation chamber in the form of liquid fuel while the tarry liquid waste is topped-down from the heating reactor vessel. The organic gas is generated which is vented due to lack of storage facility. However, the gas can be used in dual fuel diesel-generator set for generation of electricity. The process includes the steps shown ahead:
❯ There are no liquid industrial effluents and no floor washings as it is a dry process.
❯ There are no organized stack and process emissions.
❯ Odour of volatile organics has been experienced in the processing area due to some leakages or lack of proper sealing
❯ Absolute conversion of liquid-vapour was not possible into liquid, some portion of gas (about 20%) is connected to the generator. However, the process will be improved in full-scale plant.
❯ PVC plastics waste is not used and if used, it was less than 1%. In case PVC is used, the chlorine can be converted into hydrochloric acid as a by-product.
❯ The charcoal (charcoal is formed due to tapping of tarry waste) generated during the process has been analysed and contain heavy metals, poly aromatic hydrocarbon (PAH) which appears to be hazardous in nature. The source of metals in charcoal could be due to the presence of additives in plastics and due to multilayer and laminated plastics.
❯ Monitoring of process fugitive emissions in the work area as well as emissions from the engines/diesel generator sets is necessarily required (where this liquid fuel is used) for various parameters such as CO, HCl,
Styrene, Benzene, VOCs.
Plastics waste disposal through Plasma Pyrolysis
Plastics waste disposal through Plasma Pyrolysis Technology (PPT)
Plasma Pyrolysis is a state of the art technology, which integrates the thermochemical properties of plasma with the pyrolysis process. The intense and versatile heat generation capabilities of PPT enable it to dispose off all types of plastic wastes including polymeric, biomedical and hazardous waste in a safe and reliable manner.
Plasma Pyrolysis Technology
In plasma pyrolysis, firstly the plastics waste is fed into the primary chamber at 8500C through a feeder. The waste material dissociates into carbon monoxide, hydrogen, methane, higher hydrocarbons etc. Induced
draft fan drains the pyrolysis gases as well as plastics waste into the secondary chamber, where these gases are combusted in the presence of excess air. The inflammable gases are ignited with high voltage spark.
The secondary chamber temperature is maintained at around 10500 C. The hydrocarbon, carbon monoxide and hydrogen are combusted into safe carbon dioxide and water. The process conditions are maintained
so that it eliminates the possibility of formation of toxic dioxins and furans molecules (in case of chlorinated waste). The conversion of organic waste into non toxic gases (CO2, H2O) is more than 99% .
The Plastic waste disposal through Plasma Pyrolysis is a state of the art technology, which integrates the thermo-chemical properties of plasma with the pyrolysis process extreme conditions of Plasma kill stable bacteria such as Bacillus stereothermophilus and Bacillus subtilis immediately. Segregation of the waste is not necessary, as very high temperatures ensure treatment of all types 0f waste without discrimination.
The CPCB has initiated the study in association with Facilitation Centre for Industrial Plasma Technologies (FCIPT), Institute of Plasma Research (IPR) The objectives of the study are to conduct performance study of the PPT on 15 kg/hr prototype demonstration system developed by FCIPT/ IPR for proper disposal of plastics waste and also monitor air quality parameters e.g. suspended particulate matter (SPM), carbon monoxide (CO), hydrocarbons (HC), benzene, dioxins, furans etc. with regards to gaseous emissions. CPCB also proposes to undertake study on safe disposal of plastics waste using higher capacity (approx. 50 kg/hr) plasma pyrolysis system as in future and may set up prototype plasma pyrolysis plant on demonstration basis (15 kg/hr waste disposal capacity) at specific locations (hilly and pilgrimage) in consultation with State Government.
Plasma Pyrolysis is a state of the art technology, which integrates the thermochemical properties of plasma with the pyrolysis process. The intense and versatile heat generation capabilities of PPT enable it to dispose off all types of plastic wastes including polymeric, biomedical and hazardous waste in a safe and reliable manner.
Plasma Pyrolysis Technology
In plasma pyrolysis, firstly the plastics waste is fed into the primary chamber at 8500C through a feeder. The waste material dissociates into carbon monoxide, hydrogen, methane, higher hydrocarbons etc. Induced
draft fan drains the pyrolysis gases as well as plastics waste into the secondary chamber, where these gases are combusted in the presence of excess air. The inflammable gases are ignited with high voltage spark.
The secondary chamber temperature is maintained at around 10500 C. The hydrocarbon, carbon monoxide and hydrogen are combusted into safe carbon dioxide and water. The process conditions are maintained
so that it eliminates the possibility of formation of toxic dioxins and furans molecules (in case of chlorinated waste). The conversion of organic waste into non toxic gases (CO2, H2O) is more than 99% .
The Plastic waste disposal through Plasma Pyrolysis is a state of the art technology, which integrates the thermo-chemical properties of plasma with the pyrolysis process extreme conditions of Plasma kill stable bacteria such as Bacillus stereothermophilus and Bacillus subtilis immediately. Segregation of the waste is not necessary, as very high temperatures ensure treatment of all types 0f waste without discrimination.
The CPCB has initiated the study in association with Facilitation Centre for Industrial Plasma Technologies (FCIPT), Institute of Plasma Research (IPR) The objectives of the study are to conduct performance study of the PPT on 15 kg/hr prototype demonstration system developed by FCIPT/ IPR for proper disposal of plastics waste and also monitor air quality parameters e.g. suspended particulate matter (SPM), carbon monoxide (CO), hydrocarbons (HC), benzene, dioxins, furans etc. with regards to gaseous emissions. CPCB also proposes to undertake study on safe disposal of plastics waste using higher capacity (approx. 50 kg/hr) plasma pyrolysis system as in future and may set up prototype plasma pyrolysis plant on demonstration basis (15 kg/hr waste disposal capacity) at specific locations (hilly and pilgrimage) in consultation with State Government.
Polymer Coated Bitumen Roads
Polymer Coated Bitumen Road
The CPCB has undertaken a project in collaboration with Thiagarajar College of Engineering Madurai to evaluate the performance of polymer coated built roads laid during 2002-2006 in different cities. The observations are as below:
❯ The coating of plastics over aggregate improves Impact, Los Angels Abrasion and Crushing Value with the increase in the percentage of plastics.
❯ The extracted bitumen showed almost near value for Marshall stability. The entire road was having good skid resistance and texture values.
❯ All the stretches in the roads have been found reasonably strong.
❯ The unevenness index values of these roads are nearly 3000 mm/km, which indicate a good surface evenness.
❯ The plastic tar roads have not developed any potholes, rutting, raveling or edge flaw, even though these roads are more than four years of age.
❯ Polymer coated aggregate bitumen mix performs well compared to polymer modified bitumen mix.
❯ Higher percentage of polymer coating improves the binding strength of the mix.
❯ Foam plastics have better binding values.
The CPCB has undertaken a project in collaboration with Thiagarajar College of Engineering Madurai to evaluate the performance of polymer coated built roads laid during 2002-2006 in different cities. The observations are as below:
❯ The coating of plastics over aggregate improves Impact, Los Angels Abrasion and Crushing Value with the increase in the percentage of plastics.
❯ The extracted bitumen showed almost near value for Marshall stability. The entire road was having good skid resistance and texture values.
❯ All the stretches in the roads have been found reasonably strong.
❯ The unevenness index values of these roads are nearly 3000 mm/km, which indicate a good surface evenness.
❯ The plastic tar roads have not developed any potholes, rutting, raveling or edge flaw, even though these roads are more than four years of age.
❯ Polymer coated aggregate bitumen mix performs well compared to polymer modified bitumen mix.
❯ Higher percentage of polymer coating improves the binding strength of the mix.
❯ Foam plastics have better binding values.
Options for Plastic Waste Management
Options for Plastic Waste Management
Recycling of plastics through environmentally sound manner: Recycling of plastics should be carried in such a manner to minimize the pollution during the process and as a result to enhance the efficiency of the process and conserve the energy. Plastics recycling technologies have been historically divided into four general types
-primary, secondary, tertiary and quaternary.
Primary recycling involves processing of a waste/scrap into a product with characteristics similar to those of original product.
Secondary recycling involves processing of waste/scrap plastics into materials that have characteristics different from those of original plastics product.
Tertiary recycling involves the production of basic chemicals and fuels from plastics waste/scrap as part of the municipal waste stream or as a segregated waste.
Quaternary recycling retrieves the energy content of waste/scrap plastics by burning / incineration. This process is not in use in India.
Steps Involved in the Recycling Process
Selection: The recyclers / reprocessors have to select the waste / scrap which are suitable for recycling /reprocessing.
Segregation: The plastics waste shall be segregated as per the Codes 1-7 mentioned in the BIS guidelines (IS:14534:1998).
Processing: After selection and segregation of the pre-consumer waste (factory waste) shall be directly recycled. The post consumer waste (used plastic waste) shall be washed, shredded, agglomerated, extruded and granulated
Recycling of plastics through environmentally sound manner: Recycling of plastics should be carried in such a manner to minimize the pollution during the process and as a result to enhance the efficiency of the process and conserve the energy. Plastics recycling technologies have been historically divided into four general types
-primary, secondary, tertiary and quaternary.
Primary recycling involves processing of a waste/scrap into a product with characteristics similar to those of original product.
Secondary recycling involves processing of waste/scrap plastics into materials that have characteristics different from those of original plastics product.
Tertiary recycling involves the production of basic chemicals and fuels from plastics waste/scrap as part of the municipal waste stream or as a segregated waste.
Quaternary recycling retrieves the energy content of waste/scrap plastics by burning / incineration. This process is not in use in India.
Steps Involved in the Recycling Process
Selection: The recyclers / reprocessors have to select the waste / scrap which are suitable for recycling /reprocessing.
Segregation: The plastics waste shall be segregated as per the Codes 1-7 mentioned in the BIS guidelines (IS:14534:1998).
Processing: After selection and segregation of the pre-consumer waste (factory waste) shall be directly recycled. The post consumer waste (used plastic waste) shall be washed, shredded, agglomerated, extruded and granulated
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