STAGE 1 – DELIVERY OF WASTE AND STORAGE
A covered, walled area is provided for all deliveries via raised loading bays. All waste is moved by mechanical machinery onto raised conveyors where non-combustible items are removed manually. The feedstock is then deposited into the shredder unit by way of conveyor.
STAGE 2 – SHREDDER UNIT
This unit consists of an iron core-pulling machine that cuts the larger material into smaller material. The unit possesses a crushing head, capable of shredding up to five tons of material per hour. The shredder is a closed-loop, hydraulically driven system. Operating at a high rate of pressure, it produces increased torque as small displacement occurs.
STAGE 3 – HOPPER UNIT
The feedstock is broken down in to manageable sizes mechanically via the hopper unit. The Hopper consists of metal cutters and drums designed specifically to cut and mulch waste.
The hopper can be pre-loaded and is capable of containing up to ten tons of MSW along with other waste. The Hopper operates on a gravity system; feeding the main pyrolysis unit automatically.
STAGE 4 – PYROLYSIS UNIT
Pyrolysis involves an endothermic reaction through general combustion. This is done by the generation of heat reaction in the system that produces solid, liquid and gas by heating it at moderately high temperatures under no oxygen or low oxygen atmosphere.
The main parameters governing the pyrolysis process are temperature, heating rate, solid residence time, particle size and density of particles.
There are three forms of Pyrolysis: flash, fast and slow. The particular form is determined by temperature, rate and residence time. The GGII pyrolysis system shown above is of modular design. Each plant can process 20 tons of dry unsorted waste per day.
STAGE 5 – WET SCRUBBERS
Whereas only trace amounts of greenhouse gas are produced in the process of Pyrolysis, acidic gases are likely to result and therefore require removal. Wet scrubbers exist for this purpose.
The wet scrubbing unit achieves the removal of acidic, synthetic gases by utilizing a minimal amount of chemicals and a bag filter. The resulting exhaust is then cooled to 600C in a heat exchanger.
Once cooled, the exhaust gas passes through an acidic scrubber where the hydrogen chloride is removed. An alkali scrubber is used to remove any existing sulphur dioxide. Finally, the gas is reheated in the heat exchanger and expelled by means of a large fan.
STAGE 6 – GAS COOLING TOWER
Most gasification processes cool the syn-gas to 600C for conventional gas scrubbing. However, this cooling results in significant energy losses.
Our technologies compensate for this loss by utilizing the efficiency advantage that results from cleaning hot gas and burning it in a boiler or gas turbine.
GGE’s Cooling Tower filters syn-gas at 3,500C using sintered metal fillers and burns it in a gas turbine immediately. By keeping the temperature at 3,500C, tar condensation is not a problem. Further, the temperature is sufficient to remove any alkali metal chlorides.