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Comparison between pyrolysis and incinerators
Comparison between pyrolysis and incinerators
PYROLYSIS TECHNOLOGY
INCINERATION TECHNOLOGY
Minimal environmental impactand high operating reliability.
Dubious environmental compatibility, particularly in relation to the emission of micropollutants, and lower reliability in relation to the characteristics of the inhomogeneous waste.
The operation of purification of the gas stream is extremely simple since the flow of pyrolysis gas, produced in a reducing environment, is characterized by very simple molecules and is absolutely devoid of chlorinated organic compounds, precursors to the formation of dioxins. The distillation in the absence of air transforms the halogens and sulfur, mainly responsible for the macro pollution, compounds hydrogenated acids that are removed from the gas stream prior to its combustion. The thermodynamic cycle of the pyrolysis avoids, all during the whole process, the conditions that lead to the formation of dioxins and furans.
The uneven flow of material in thermodynamic conditions which are difficult to control (with high temperatures, oxidizing environment, presence of water vapor) make it difficult to control the formation of halogenated organic compounds and compromise the reliability of the system against micro-organic chlorides. In such conditions it is difficult to avoid formation of dioxins and furans, compounds expensive to remove from the high volume of gases produced by combustion.
The pyrolysis of waste produces a quantity of gas about 10 times lower than that produced with conventional technologies of direct combustion. Treatment of the gas stream prior to its combustion (in relatively small amount as not yet diluted by air) makes it considerably easier and cheaper the removal of undesirable compounds.
Treatment gaseous effluent downstream of the combustion and then on a flow quantitatively important to the process makes it very expensive a gas cleaning process. To obtain as complete as possible a combustion of waste, is in fact work with an excess of air equal to 1.5 - 2.5 times the amount strictly necessary.
The pyrolysis process, by its nature endothermic, is conducted under reducing conditions at relatively low temperatures, close to 600 °C. This facilitates the control of temperature and of the whole process, drastically reduces the quantity of effluent gaseous products and avoids the formation of toxic side effects.
The incineration processes are exothermic oxidation processes, characterized by temperatures exceeding 1,000 °C. Controlling the temperature of the combustion process is difficult, as it is influenced by the variation of the flow of the waste input (high inertia of the system).
No production of liquid waste, which then require its own water treatment and purification section, resulting in economic and environmental benefits of the process.
Need for an important section for the treatment of liquid waste, with all the related economic and environmental issues.
The low temperature of the pyrolysis process and the practical absence of high turbulence inside the reactor dramatically reduces the entrainment of dust and particulate in the pyrolysis gas.
The direct combustion of a heterogeneous product such as a refusal, with the formation of several products with complex molecules and the presence of unburned residues makes it difficult a perfect management of the combustion process.
Since the pyrolysis process has, as the main resulting product, a fuel in gaseous form (syngas), its combustion is clean and gives energy recovery.
The incineration furnaces can be sensitive to variations in calorific value of the material, particularly waste with a high calorific value (tires) can damage the plant.
The pyrolysis technology is an universal waste disposal system, to be applied to a wide range of waste.
Incineration plants produce a high quantity of slag, up to 30% of the burned waste, the disposal of this kind waste is very problematic.
As a solid residue, the pyrolysis process, produces only vitrified slag that are completely inert (not releasing any toxic elements in the environment). Also the powders resulting from the process of purification of combustion gases before their release into the atmosphere are led inside the plant and vitrified.
The major shortcomings of incineration, can be summarized as follows:
- Incomplete combustion of solid waste
- Large production of toxic solid waste
- Large volume of fumes to be treated
- Dangerous emissions into the atmosphere
- Impairment losses of inorganic components of the waste and so it becomes evident the distinctive features of the pyrolysis process that we propose
Advantages of our plants with pyrolysis process
The fumes and vapours of the pyrolysis process, suitably eliminated by a tube bundle heat exchanger, give us the possibility of obtaining diesel fuel with a low sulfur content which can be reused as fuel in one or more generators for the production of electricity.
The exhaust fumes of the generators, although emitted by catalytic converters in accordance with the law, are further eliminated in order to reduce any possible form of pollution. In fact it can be seen only a trace of water vapor coming out from the installation.
The electricity is sold online to the distribution companies such as Enel. Edison, Sorgenia etc. etc.
The other by-products extracted from the process as steel and carbon-black are sold to the various industries, i.e. the steel to steelworks, the colorants to the paint industries, the carbon black to the tire factories or the toners for the printers manufacture.
The Syngas, on the other hand, is captured, compressed in special tanks and reused in the same furnace together with the propane gas as gas heating to complete the daily requirement in the pyrolysis process.
The oven designed by Rep Italia Srl is able to dispose 2,500 tires per day, just to meet a daily production of 24 MW equal to 24,000 Kw/h.
The whole process is controlled by a PLC checking continuously the times of loading and unloading and the optimum level of temperatures.
All the components of our plant are strictly adhering to all the accident prevention regulations, all marked CE.
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