2017 November, SweetcrudeReports
equally as harmful to the environment as the plastic itself. Various technologies are being developed to overcome the drawback of plastics, namely, their nonbiodegradability. Though work has been done to make futuristic biodegradable plastics, there have not been many conclusive steps towards cleaning up the existing problem. Recycling waste plastics into reusable plastic products is a conventional strategy followed to address this issue for years. However this technique has not given impressive results as cleaning and segregation of waste plastics was found difficult.
Waste plastic conversion plant
Conversion of waste plastics to oil CONTINUED FROM PAGE 40
very high doses these chemicals can disrupt the endocrine (or hormonal) system. Researchers worry particularly about the effects of these chemicals on children and what continued accumulation means for future generations. Plastics constitutes in two main categories. It is thermoplastics and thermoset plastics. Thermoplastics make up 80% of the plastics and thermoset plastics make up of remaining 20% of plastics produced today. Thermo plastics can re-melt or re-mould and therefore it’s recyclable easily but thermoset plastics cannot remelt or reshape and therefore it is difficult to recycle Examples of Thermosets Epoxide (EP) Phenol-formaldehyde (PF) Polyurethane (PUR) Polytetrafluoroethylene - PTFE Unsaturated polyester resins (UP). Examples of Thermoplastics Acrylonitrile butadiene styrene – ABS Polycarbonate - PC Polyethylene - PE Polyethylene terephthalate - PET Poly(vinyl chloride) - PVC Poly(methyl methacrylate) PMMA Polypropylene - PP Polystyrene - PS Expanded Polystyrene – EPS Uses of different types of
Pyrolysis Process block diagram plastics. Polyester-Textile fiber PET (Polyethylene Terephthalate)-Carbonated drink bottles, plastics film PE (Poly Ethylene)Supermarket bags, plastics bottles HDPE (High Density Polyethylene) -Milk jugs, detergent bottles, thicker Plastics film, pipes LDPE (Low Density Polyethylene)-Floor tiles, shower curtains, cling film PVC (Polyvinyl Chloride)Agriculture (fountain) pipe, Pipes, window frame, sheets for building material PS (Polystyrene)-Foam use for insulation of roofs and walls, disposal cups, plates, food Container, CD and cassette box. PP (Polypropylene)-Bottle caps, drinking straws, Bumper, house ware, fiber carpeting and rope
Biodegradability Plastics are nonbiodegradable material that resists microbial attack. Though work has been done to make futuristic biodegradable plastics, there have not been many conclusive steps towards cleaning up the existing problem because prices of biodegradable plastics is more than petrochemicals based plastics. It may be due to high
cost of production and low availability or high cost of raw materials. Some degradable plastics have been developed, but none has proved compatible with the conditions required for most waste landfills. Thus, there is an environmental problem associated with the disposal of plastics. 6.
Recycling Technologies 1. Mechanical Recycling of waste plastics into reusable product is difficult and unfeasible due to contamination of p l a s t i c s , difficulty to identifying and separating different type of
plastics. 2. Uncontrolled incineration of plastics at higher temp above 850 deg Celsius to produces polychlorinated dibenzo-pdioxins, a carcinogen (cancer causing chemical).Open-air burning of plastic occurs at lower temperatures, and normally releases such toxic fumes and many oxide gases. So flue gases treatment is necessary to protect the environment and avert health problems in incineration plant. 3. Chemical recycling could lead to useful raw materials via
Tyre-recycling- Pyrolysis plant Plastics in land fill area leaching of toxins into ground water. Over the years, there have been various solutions proposed – diversion, burning, etc.; however, nothing to date has proven to be a truly effective or environmentally responsible solution to the burgeoning global landfill problem. In fact, many existing solutions have been just the opposite: costly, energy inefficient or
by degradation and monomerization of plastics waste, but no method of this primary recycling currently available. The degradation of some plastics into chemicals has been reported in research level. Gasification and blast furnace of plastics waste to produce gases that are carbon dioxide, nitrogen, carbon mono oxide, hydrogen and methane at higher temp above 800 deg. Celsius. 4 Pyrolysis of waste plastics
into fuel remains the best means of conserving valuable petroleum resources in addition to protect the environment. This process involves catalytic degradation of waste plastic into fuel range hydrocarbon i.e. petrol, diesel and kerosene etc. A catalytic cracking process in which waste plastic were cracked at very high temperature, the resulting gases were condensed to recover liquid fuels. Type of plastics also effect the rate of conversion of into fuel and the results of this process are found to be better than other alternate methods which are used for the disposal of waste plastic., It’s only now, with the Plastic to Oil technology, that there is a solution that is not only economically viable, but that is remarkably simple and “green” as well. ADVANTAGES: Problem of disposal of waste plastic is solved. Waste plastic is converted into high value fuels. Environmental pollution is controlled. Industrial and automobile fuel requirements fulfilled to some extent at lower price. No pollutants are created during cracking of plastics. The crude oil and the gas can be used for generation of electricity. This will aid in the reduction of petroleum Imports and development of alternative sources of energy. Pyrolysis of Plastics The essential steps in the pyrolysis of plastics involve (1) Evenly heating the plastic to a narrow temperature range without excessive temperature variations, (2) Purging oxygen from pyrolysis chamber, (3) Managing the carbonaceous char byproduct before it acts as a thermal insulator and lowers the heat transfer to the plastic, (4) C a r e f u l condensation and fractionation of the pyrolysis vapors to produce distillate of good quality and consistency.
Advantages of pyrolysis process are (A) Volume of the waste is significantly reduced (<50–90%), (B) Solid, liquid, and gaseous fuel can be produced from the waste, (C) storable/transportable fuel or chemical feed stock is obtained, (D) Environmental problem is reduced, (E) Desirable process as energy is obtained from renewable sources like municipal solid waste or sewage sludge.