Other Emerging Processes of Energy Recovery
(i) Slurry Carb Process:
This process has been developed by a company in USA to convert municipal solid waste into fuel oil. It is used in conjunction with a wet resource recovery process to separate out the recyclables. The received waste is first shredded and placed in an industrial pulper. The heavier and denser inorganic material sink to the bottom of the water-filled pulper from where it is easily removed. The remaining waste slurry (organic fraction) is subjected to violent pulping action, which further reduces the size of its constituents. The pulped organic waste is then subjected to high pressure and temperature whereby it undergoes thermal decomposition / carbonisation (slow pyrolysis) to fuel oil.
(ii) Plasma Pyrolysis Vitrification (PPV) / Plasma Arc Process:
This is an emerging technology utilising thermal decomposition of organic wastes for energy / resource recovery. The system basically uses a Plasma Reactor which houses one or more Plasma Arc Torches which generate, by application of high voltage between two electrodes, a high voltage discharge and consequently an extremely high temperature environment (between 5000- 14,000oC. This hot plasma zone dissociates the molecules in any organic material into the individual elemental atoms while all the inorganic materials are simultaneously melted into molten lava.
The waste material is directly loaded into vacuum in a holding tank, preheated and fitted to a furnace where the volatile matter is gasified and fed directly into the plasma arc generator where it is pre-heated electrically and then passed through the plasma arc dissociating it into elemental stages. The gas output after scrubbing comprises mainly of CO and H2. The liquefied produce is mainly methanol.
The entire process is claimed to safely treat any type of hazardous or nonhazardous materials. It has the advantage that the NOX (oxides of Nitrogen) and SOX (oxides of Sulphur) gases emissions do not occur in normal operation due to the lack of oxygen in the system.
Some US companies offering PPV technology are reported to be setting up some demonstration units based on this technology in Malaysia and Singapore.
