a comparison between pyrolysis anD
incineration plant

The pyrolysis process we have proposed is much more adequate than the incineration technologies.
Incineration takes place in a furnace, usually fitted with a moving grate, specially designed for the incineration of fuels that feature a low calorific value and a lack of homogeneity as far as quality and size are concerned. Nonetheless, the direct combustion has a series of obvious advantages:

  • The reduction by 90% and 70% respectively  of the initial volume and weight
  • The residues are completely sterile and stable
  • The likelihood of salvaging a good portion of the energy stored in the materials
Nonetheless, if we compare incineration to the pyrolysis we proposed the shortcomings of combustion become stark. Traditional incineration methods are exothermic and are characterized by a wider range of temperatures (800÷1400°C).

Due to the variable composition of the products, regulating the temperature inside the incinerator entails constant changes in the power systems, leading to difficult management; from these results a plant that does not meet the requirements for an optimal operation.

Experts have leveled heavy criticism against traditional incinerators, pointing towards both the management and operation difficulties and on the possibility that highly polluting materials be dispersed in the atmosphere. The complex and expensive systems meant to treat and eliminate the fumes involves heavy investment, it increases management and maintenance costs and, to top it off, they haven’t even provento be eco-friendly.

THE COMPARISON

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impact on the environment
Pyrolysis: minimum impact on the environment and maximum security of the process. Disposal plants are simple and error-proof.

Incineration: doubtful environmental compatibility (particularly in relation to micro-pollutant emissions) and uncertain reliability. Abatement plants characterized by all too complicated plant and management designs, as well as by very high costs.

GAS treatment
Pyrolysis: the treatment of the gas flow before the combustion, it doesn’t allow for the dilution of combustion air. Waste pyrolysis produces 10 times less gas than traditional combustion.

Incineration: gaseous effluent treatment takes places downstream of combustion and therefore on an important mass current (diluted by combustion air). To obtain combustion as complete as possible, work is carried out with an excess of air equal to 1.5-2.5 times the stoichiometric quantity necessary.

thermic process
Pyrolysis: the pyrolysis, an endothermic process, is conducted at low temperatures (aprox. 500°C). This makes for a  Acest fapt facilitează controlul temperaturii și al procesului, reduce drastic cantitatea de eflueți gazoși și previne formarea produșilor nedoriți.

Incineration: exothermic oxidative processes, characterized by combustion temperatures above 1,000 ° C. Temperature regulation difficult to manage as it can only be carried out by varying the flow rate in the supply (high inertia of the system).

purification operation
Pyrolysis: the purification operation of the gas stream is extremely simple as the pyrolysis gas produced in a reducing, and not yet burned, environment is characterized by structurally simple molecules and absolutely free of chlorinated organic compounds (PCDD-PCDF). Distillation in the absence of air turns the halogens and sulfur into hydrogenated acid compounds which are broken down and removed from the pyrolysis gas stream before its combustion. The cycle avoids, at every point of the implant, the contemporaneity of the conditions that lead to the formation of dioxins, solving the serious problem of organic micro-pollution.

Incineration: complications in the control of PCDD-PCDF formation: difficulties emerge both in the design phase and in that of combustion management and make doubts arise about the reliability of the system against organo-chlorinated micro-pollutants.

treatment of liquid waste
Pyrolysis: recovery water treatment section with obvious economic benefits.

Incineration: need for an important section for the treatment of liquid waste, with all the ensuing issues.

C TREATMENT
Pyrolysis: partial gasification of C, the rest remains in the residue as coal mixed with inorganic components.

Incineration: complete oxidation of all the Carbon stored in the CO2 waste and its consequent dispersion in the atmosphere with the possibility creating premises for microclimatic variations.

dust and particulates
Pyrolysis: the low temperature and the practical absence of convective movements inside the reactor prevent the particulate entrainment.

Incineration: significant presence of dust and particulates in the fumes, due to the movement of waste on the grid and the considerable excess of air.

COMBUSTION
Pyrolysis: easy management of combustion linked to the type of fuel (pyrolysis gas in aeriform phase).

Incineration: direct combustion of a heterogeneous product, resulting the formation of various combustion products characterized by complex molecules and the presence of unburnt substances.

metals
Pyrolysis: complete recovery of metals in non-oxidized form.

Incineration: loss of metals scraps with low melting point (aluminum) and decrease in value of ferrous scrap due to oxidation.

energy recovery
Pyrolysis: rhe carbon component, residual from the pyrolysis of organic components, is easy to use as fuel (PCI ~ 5200 kcal / kg) flexible energy recovery.

Incineration: rigid energy recovery system, with on-site production of electricity and auxiliary fuel consumption in the afterburner.

process temperature
Pyrolysis: low process temperature favors the life of refractory linings and mechanical parts. The nature and quantity of circulating gases prevents erosion and corrosion and significantly reduces maintenance costs.

Incineration: high process temperatures. Direct combustion of waste with the formation of aggressive compounds. High maintenance costs.

disposal
Pyrolysis: nearly universal disposal system, being able to be applied to various categories of incoming materials.

Incineration: sensitivity of the grids to waste characterized by a high calorific value (used tires).

investment costs
Pyrolysis: limited investment costs.

Incineration: significant investment costs.

operating costs
Pyrolysis: low operating costs.

Incineration: management costs on average levels.

implementation
Pyrolysis: simplicity of implementation.

Incineration: complex plants, especially in the treatment of fumes.

process management
Pyrolysis: simple process management.

Incineration: complex management of the process with the problem of the qualification of the operating staff.

management
Pyrolysis: long-term reliability.

Incineration: necessity of continuous maintenance.

plant scale
Pyrolysis: possibility to vary the plant scale in a modular way.

Incineration: scale rigidity (large systems).

DELIVERY AND ASSEMBLING TIMES
Pyrolysis: relatively short delivery times, assembly and start-up.

Incineration: high production and start-up times Plants.

The conspicuous shortcomings of the incineration can be summarized in incomplete combustion of solid residues, large volumes of fumes to be treated, dangerous emissions in the atmosphere, impossibility of storing the energy produced, loss of value of inorganic components, etc. By contrast, they highlight the peculiarities of the proposed pyrolysis process.

Existing pyrolysis facilities

There are known many types of pyrolysis plants that use gas combustion to produce thermal and electrical energy, by means of endothermic engines.

It is a well-known fact that endothermic engines have a conversion rate twice as high as common turbines (based on either vapors or ORC) and that is why they are preferred as far as the stimulation of biomass-based electrical energy is concerned.

As of late, researchers have not focused as much on pyrolysis as on the sustainable systems able to purify synthetic gas, on completing the energetic cycle and avoiding pollutants. That is why nowadays the process also encompasses:

  • The catalytic treatment of the syngas, which involves simultaneously treating the gas and, as a byproduct, producing other types of gas:
  • The full reuse of liquid biofuels resulted from the gas condensation phase.

Taking into account the aforementioned elements and the fact that pyrolysis represents the core of the entire system; we can conclude that it enables a simple and tamper-proof implementation in the field of power conversion.

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