Advantages and Disadvantages of Energy Recovery
The valuation has a number of advantages:
- Reduction of waste volume by up to 90%.
- Energy recovery.
- The ashes are more stable than the starting waste.
Energy recovery from waste is getting energy from burning. The calorific value of waste is variable, in the case of hydrocarbon plastics is estimated to be comparable to that of the oil with some environmental benefits as not to generate sulfur oxides, which cause acid rain. However, the combustion of PVC generates a 50% energy than before.
The disadvantages are:
- The indiscriminate burning of waste without separation occurs as a result of certain products of combustion very toxic. The presence of PVC in the mixture contributes to the combustion gases hydrochloric acid in the presence of organic matter can lead to toxic products arising from dioxins and dibenzofurans.
- The product of combustion ash containing heavy metals such as cadmium in quantities considered hazardous and should receive special treatment as hazardous waste.
As a result of the above two points need to make large investments in technology.
If recyclable materials are incinerated in other ways is a valuable resource consumption.
In response to these problems of incineration technology has developed significantly in recent years to reduce greenhouse gases and fumes. The incinerators operate at high temperatures to destroy dioxins and furans, they usually do at 1000 ° C. On the other side and to ensure the composition of the gases and washing units incorporate appropriate filters. All of this strictly regulated by both European and national regulations.
There are several process technologies: grill, fluidized bed and plasma. The aim of all is to achieve complete combustion and emit to the atmosphere only carbon dioxide and water, having been retained heavy metals, acid gases and particulates generated during combustion. Of all the fluidized bed technology allows emissions below the limits. Good contact is used in a combustion chamber of the afterburner with a bed of sand heated to 850 ° C in the presence of a higher percentage to 6% oxygen in a period of at least two seconds.
Recently the company Solvay, manufacturer of chlorine, including PVC, has developed a combustion technology (NEUTREC ®) that ensures the control of gases emitted into the atmosphere and the recovery of ash generated. The process is based on the incorporation of dry sodium bicarbonate in the gas stream. And major improvements are achieved with respect to semi-wet processes used before. The novelty lies in the possibility of separating the residual solids content of heavy metals and organic compounds in the chemical recycling.
The gases have to be in contact with sodium bicarbonate for two seconds at temperatures above 140 ° C to achieve complete neutralization. Then the gases pass through bag filters to retain dust particles and one for particles of activated carbon to retain heavy metals dioxins and furans.
Posted in 
Tags: