1.1.         Incineration power plants

INCINERATION is a waste treatment technology that involves burning commercial, residential and hazardous waste. Incineration converts discarded materials, including paper, plastics, metals and food scraps into bottom ash, fly ash, combustion gases, air pollutants, wastewater, wastewater treatment sludge and heat.

It follows several steps illustrated in figure 1-1.

Figure 11: steps in a incineration an power plant

The ENERGIZE multistage grate is the core and the bottom surface of the furnace. It carries and transports the burning solid matter from the feeding section to the ash extractor.

The grate consists of identical elements grouped in 3 zones:

Drying zone, combustion zone, burnout zone.

1. In the drying zone, moisture in the waste is evaporated by the heat in the furnace and the radiation from the first empty pass which is positioned just above this zone.

2. In the combustion zone, the actual combustion takes place.

3. The burnout zone is a buffer to guarantee the burnout quality and to cool the ashes.

A step between each zone causes the waste to drop from one zone to the next, creating the necessary mixing of the burning matter[1].

The 3 zones illustrate in the figure 1-2.

Figure 12: illustrating of the incineration power plant zone

1.2.         Study of literature

There are many applications of waste incineration power plants, especially in Europe, see Figure 1-3, and it is necessary to study them. But it is impossible to view published studies in internet; we can only see the incineration power plant's design with global studies.

Figure 13: Distribution of incineration power plant in Europe

Figure 14: An incineration power plant in (A) Torsviksverket in Jönköping (B) Roskilde, Denmark (C) Esbjerg Denmark (D) near Bergen (Oslo).

An incineration plant in Sweden Figure 2-2 (A) represents a similar amount of waste in the industry as well. Waste incineration provides heat corresponding to the needs of 810,000 homes, around 20 per cent of all the district-heating produced. It also provides electricity corresponding to the needs of almost 250,000 homes. International comparisons show that Sweden is the global leader in recovering the energy in waste[2].

In Roskilde, Denmark figure 2-2 (B) when waste from nine surrounding municipalities and from places abroad will be incinerated at the Roskilde plant. According to its developer KARA/NOVEREN, this will be enough to produce electricity for around 65,000 homes and heat for around 40,000 homes[3].

We can say that the incineration power plant of in Esbjerg, Denmark figure 2-2 (C), attached with some historic study concerning development of the incineration power plant design and CFD information[4] in figure 2-3:

Figure 15: CFD plot for assessment of residence time in an afterburning chamber in Esberg, Denmark incineration power plant.

Christoffer Back Vestli says, communications adviser for the Oslo in Bergen figure 2-2 (D): municipality. "At the moment, the city of Oslo can take 410,000 tonnes of waste a year and we import 45,000 tonnes from the UK. Europe as a whole currently dumps 150m tonnes of waste in landfills every year, so there is clearly great potential in using waste for energy."[5]

1.3.            Arguments supporting and against incinerations

Usage of incineration for waste management is divisive. The debate for incinerators generally involves business interests, regulations of government, activists of environment and citizens.


 

Arguments supporting incinerations

The first concern for incineration stands against its injurious effects over health due to production of furans and dioxin emission. However, the emission is controlled to greater extent by developing of modern plants and governmental regulations.

Incineration plants are capable for producing energy and can substitute power generation plants of other sort.

The bottom ash after the process is completed is considered non-injurious that still is capable for being land filled and recycled.

Fine particles are removable by processing through filters and scrubbers.

Treating and processing medical and sewage waste produces non-injurious ash as product.

Arguments against incinerations

Extremely injurious matter needs adequate disposing off. This requires additional miles and need special locations for land filling this material.

Although after a lot of regulations and restrictions and developments concerns are still alive about emission of furans and dioxins.

Incinerating plants are producers of heavy metals, which are injurious even in minor amounts.

IBA (Incinerator Bottom Ash) is consistent over a considerably high level of heavy metals and can prove fatal if they are not disposed off or reused properly.

Initial investment costs are only recovered through long periods of contract for incinerating plants.

Local communities always have opposed the presence of incinerating plant in the locality.

The upheld view is to recycle, reuse and waste reduction instead of incineration[6].

1.4.         History

In the past, incineration was conducted without separating materials thus causing harm to environment. This unseparated waste was not free from bulky and recyclable materials, even. This resulted in risk for plant workers health and environment. Most of such plants and incinerations never generated electricity.

Incineration reduces the mass of the waste from 70 to 80 percent. This reduction depends upon the recovery degree and composition of materials. This means that incineration however, does not replace the need for landfilling but it reduced the amount to be thrown in it.

Incineration comes with a number of benefits in specific areas like medical wastes and other life risking waste. In this process, toxins are destroyed when waste is treated with high temperature.

Incineration or thermal treatment of waste is much popular in countries like Japan where there is scarcity of land. The energy generated by incineration is highly demanded in countries like Denmark and Sweden. In the year 2005 it was estimated that 4.8 percent of the electricity consumed by Danish nation was produced by incineration and the amount of heat was some 13.7 percent out of total. Other than Denmark and Sweden many European countries are recovering heat and electricity from waste[6].

 

References

[1] WASTE to ENERGY INTEGRATED SOLUTIONS FOR THE THERMAL TREATMENT OF TOXIC AND NON-TOXIC; WATERLEAU protecting the 4 elements: WASTE Radioweg 18, 3020 Herent (Leuven), Belgium t. +32 (0) 16 65 06 57 - f. +32 (0) 16 65 06 63 info@waterleau.com - www.waterleau.com

[2] AVFALL SEVERAGE; Swedish Waste Management. Avfall Sverige AB Literature references, www.avfallsverige.se Prostgatan 2, SE-211 25 Malmö +46 40-35 66 00 +46 40-35 66 26 info@avfallsverige.se www.avfallsverige.se

[3] Roskilde's glowing incinerator powers 65,000 households STU ROBARTS SEPTEMBER 16, 2014

[4] By Heron Kleis, Babcock & Wilcox Vølund and Søren Dalager, Rambøll, 100 YEARS OF WASTE INCINERATION IN DENMARK, From Refuse Destruction Plants to High-technology Energy Works

[5] Trash to cash: Norway leads the way in turning waste into energy, UK cities pay to send rubbish to Norwegian incinerators, but green campaigners warn of dangers

[6] http://www.wrfound.org.uk/articles/incineration.html Copyright 2009 , Waste Management Resources