ProcessEnvironm. ImpactContact Us

Energy and Hydrogen the Process

 

Introduction The production of electric energy from renewable sources constitutes an important alternative to the usual forms of electric energy production. Currently, following the application of legislative measures subsequent to the law of energy savings and the reduction of the greenhouse effect (Kyoto Protocol), electric energy production is generally promoted thanks to a tariff incentive, such as the form of energy production from renewable sources.

Pyrolysis/gasification of RDF: Pyrolysis/gasification or pyrogenation indicates a chemical decomposition process generated exclusively by an intervention of thermal energy.  The pyrolysis/gasification processes were among the first reactions realized by alchemists and chemists. Today’s industry adopts on a large scale processes of pyrolysis/gasification in the chemical and petrochemical field. Pyrolysis/gasification is a treatment technology of substances of a prevalently plastic origin and other high caloric contents and is receiving ever more attention for its characteristics which, besides favoring the recovery of material and energy, facilitate process control. 
In the absence of air, so in a reducing environment, the pyrolysis/gasification provokes the thermo-chemical decomposition of the material. Applied to RDF treatment, pyrolysis/gasification technology offers significant advantages. The process, by its endothermic nature, instigates the scission of the complex molecules which form rubber, plastics and cellulose components, and other complex chemicals, such as tires and particleboard, other RDF components, transforming them into structurally more simple molecules. The main variables governing pyrolysis/gasification, as in other chemical processes, are: temperature, dwelling time and pressure. Today, among the new complex-technology solid waste management systems, pyrolysis/gasification proposes itself as an alternative to incineration systems. Field experts have actually given much criticism to traditional incinerators, challenging, beyond management and operation difficulty, the possibility of highly pollutive products being dispersed in the atmosphere despite the presence of costly and monumental demolition systems and steam purification.

Process Phases

  • The system is made up of the following phases:
  • Loading.
  • Pyrolysis/gasification reactor.
  • Pyrolysis/gasification-vitrification combustion chamber.
  • Steam treatment unit.
  • Check, electrical system, control panel.
  • Waste collection devices.
  • Requirements for avoiding noise pollution

The material is transported through the intermediate silo to the unit’s reactor, by means of a screw feeder and conveyor. The material is diffused and finely distributed (homogeneously) on the entire surface of the pyrolysis/gasification reactor, where the thermolic reaction occurs through the heat accumulation from 1200 to 1600 C° and, in the underlying part of the reactor, the pyrolysis/gasification of the remaining heavier components of the material and carbon particles.  

Process control: The gasification process, by its endothermic nature, is conducted in reduced conditions and elevated temperatures of 1200-1600°C. Temperature control is automatic by means of auxiliary oxygen and methane burners.  The use of oxygen instead of air drastically reduces the amount of gaseous effluents produced, while the elevated temperature in the reactor prevents the formation of undesired toxic products

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Home][Waste Sorting line][Energy and Hydrogen]

Copyright (c) 2006 CO.F.A.M.M. srl. All rights reserved.

bucciarello@cofamm.it

THE GAS CONDITIONING
The amount of char, tars and alkali, even if lower compared to other systems, has to be considered over tolerance level. Therefore, a gas cleaning system is necessary. This system allows, moreover, to guarantee pollution emissions levels lower than safeguard norms and to improve the power plant, converting the tar in useful gas or recovering heat (for the steam generator) or minerals (for agricultural scopes); even if it represents an additional cost. Numerous methods for the gas clean-up exist which can be divided into two main categories described by operation temperatures: Cold clean-up consists in mechanical particles removal via cyclone, bag or sand filters and water jets (scrubber). Gas cooling is always necessary. Warm clean-up consists of a first stage constituted by a cyclone, followed by a tar remover (tar cracker) and a particulate remover (ceramic filters); all these systems work at high temperatures so the gas cooling is avoided [2].  Gas cooling always causes energy loss and thermochemical pollution but it is the system more experimented. Moreover the we have developed a system that can reduce the energy loss and the thermo-chemical pollution. In fact we use an oil heat exchanger, easy cleanable, to cool the gas and to evaporate the cleaning water. Furthermore the evaporated part of these water is the necessary steam for the “reformer” and the  residual is sent in the combustion chamber. In this way the required energy to cool the gas is used to generate the steam process and no polluted water is discharged. In practice the reformed gas is cooled, treated with an electro wet precipitator, a quenched and two final filter (carbon and fine filters). After heating the heat carrier and the combustion air the combustion gas is cleaned with traditional systems (sleeve filter, lime treatment …). Finally, the cleaned reformed gas is stored in a tank to smooth the pressure drops and to feed independently the power unit.