The municipal solid waste (MSW) gasifier suppliers in India have come a long way from their initial days when there was not much of a range of designs. With the evolution of the gasification technique, the manufacturers have experimented enough to launch numerous designs depending upon various parameters. Some of the factors that determine the design of an MSW gasifier are given below.
Heat Source
Your MSW gasifier supplier may provide you an allothermal or an autothermal gasifier. The key difference is the supply of heat to the reactor for conducting the process of gasification. In allothermal gasifiers, the reactor relies on an external source of heat. It may be attached to circulated hot bed material or a heat exchanger to serve the purpose. An autothermal reactor is self-sufficient in that heat is generated inside the gasifier through partial oxidation. Each design may be suitable for a different purpose; therefore, careful consideration should be given to choosing between the two.
Oxygen Source
The oxygen required for gasification may be supplied from the surrounding air or by producing purified oxygen by using a cryogenic air separation unit (ASU). When the surrounding air is used, the design is referred to as an air-blown gasifier. These gasifiers involve lower capital costs, however, the quality of syngas produced is also lower. This is due to the mixture of other gases especially nitrogen in the air which dilutes the syngas. An ASU requires more investment in terms of special equipment, but it offers a syngas of nearly 300 considerably higher Btu.
Feedstock
The gasifiers also vary depending upon the type of feedstock used for the process. The operators may decide to use dry feedstock or slurry feed. The slurry contains water, therefore, the efficiency of the gasifier is lower. This is because a proportion of fuel is burnt in vaporizing the water from the slurry. This design, however, is cheaper than the other that requires dry feedstock. Using dry feedstock is more efficient in general and involves more investment.
Syngas Cooling Method
The gas generated by the process of gasification needs to be cooled down to 100˚C before utilizing it for industrial purposes. The syngas may be brought in direct contact with cool water where some of the vaporized water mixes with syngas. To remove this water from syngas, a series of condensing heat exchangers are used. This design is relatively cheaper and produces low-quality syngas. Another method is to use a series of heat exchangers to absorb the heat from the syngas resulting in lowering the syngas temperature.
