incinerators are used to combust organic substances contained in waste.
Incineration converts solid waste into ash, flue gas and heat. Incineration is
the main alternative to landfills, which hold solid waste in a contained area.
Modern solid waste incinerators separate most dangerous gases and particulates
from the flue gas produced during incineration.
does not completely eliminate waste, it does however reduce such waste to 10%
of its original amount. Incineration is a method of waste management which is
quickly taking a prominent role for municipal authorities all over the world.
The introduction of
smokeless incinerators however would aid in the monitoring and decreasing of
the environmental impact and other implications posed by incineration systems.
Intended audiences for this system would be local
government municipalities with the intention of reducing waste and providing a
means of conserving the environment and resources.
reuse of materials is a matter of great importance, especially in modern
recovery of some if not all of the generated energy is considered the best
method of waste management and ranks over plain incineration and landfill.
Landfills are the most commonly practiced form of waste management, but the
huge requirements of land and the fact that such landfill adds to pollution of
groundwater and air by the formation of leachates and gases have made corporations
and governments wary of this method of waste disposal.
therefore adhere to and address some of these environmental impacts and as such
these systems are deemed to be more beneficial to the environment. These incinerators have an efficient
emission control system that
uses multiple techniques for the elimination, at source, of potential hazardous
emissions. These incinerators eliminate emissions through a
sophisticated system that
automatically controls the rate of combustion. These
incinerators are used in conjunction with top-mounted chimneys with accurate
draught control. If the incinerator is fitted with a scrubber or dry filter, a
mechanically induced draught system must be
installed, then comes the introduction sensors and control
dampers for these particular applications.
incineration of most wastes requires the addition of heat for the drying and
ignition of waste and
for smoke elimination as such, smokeless incinerators can be fitted with
The advantages and
disadvantages of incinerators however, still need to be properly debated before
installing such dynamic systems.
to Table 1.0, consider the advantages and disadvantages of smokeless incinerators.
Reduces volume of solid
Incinerators reduce waste
volume by approx. 95% and reduce the
original waste by around 80-85% although the exact percentage will be
dependent on the constituent materials of solid waste. Although it does not
completely eliminate the need for landfills, it definitely reduces the amount
of land needed
Incineration plants are
expensive to build, operate and maintain. These high costs encourage waste
generators to seek alternative methods to deal with waste
Power and Heat Generation;
Adhering to inevitable and
continuing increases in energy costs, the heat and energy generated from
these incinerators can be geared towards the production of electricity
through mechanisms such as steam turbines
Even though incineration
pollution control technology is evolving, for example with the production of
smokeless incinerators, it has been found that even with controls in place,
some remaining dioxin still enters the atmosphere
Research shows that incinerators
produce less pollution than landfills
Increased Waste Production;
Incinerators have the
capacity to deal with a large volume of waste at any given time an d as such,
this may in some cases be seen as an incentive to increase waste production
Filters Trap Pollutants;
Modern smokeless incinerators
use filters to trap dangerous gases and particulate matter such like dioxin
Waste incineration plans can
be located in close proximity to locations where waste is generate, which
decreases the costs and energy associated with transporting waste
Table 1.0: Advantages and
Disadvantages of Smokeless Incinerators
The structure of a smokeless
Figure 1: Basic Structure of an OLPY
The main attributes of an
incineration system include;
The rotary kiln (the primary
An afterburner (the secondary
An air pollution control and
An additional necessity, of
course, is a waste product,
whether solid or liquid, for the incinerator to burn.
of an incinerator should be constantly
monitored and maintained in order to ensure optimal efficiency and also to
ensure that it does not pose a threat to the workers, environment or the public
How does the smokeless incinerator work?
process of incineration, incinerators reduce the waste by burning it after the
incinerator is initially fired up with gas or other combustible material. Flue
gases are then sent to scrubbers which remove all dangerous chemicals from
them. To reduce dioxin in the chimneys where they are normally formed, cooling
systems are introduced in the chimneys.
is a more comprehensive synopsis of the processes of a smokeless incinerator.
In incineration applications, the fuel is
predominately waste (although fossil fuels may be co-fired) and the oxygen
source is air. The flame zone of a well-designed incinerator is sufficiently
hot to break down all organic and many inorganic molecules, allowing reactions
between most volatile components of the waste and the oxygen and nitrogen (N2)
The furnace is designed to produce good mixing of the
combustion air and the gases and vapors coming from the burning waste. In parts
of the furnace where combustion is not complete, combustible components of
organic compounds are burned off, leaving the incombustible particulate matter
known as fly ash entrained in the flue gas. The incombustible portion of the
waste (known as bottom ash) is left behind. Optimal design and operation of a
furnace requires attention to incineration temperature, turbulence of the gas
mixture being combusted, and gas-residence time at the incineration
The temperature achieved is the result of heat
released by the oxidation process, and has to be maintained high enough to
ensure that combustion goes to completion, but not so high as to damage
equipment or generate excessive nitrogen oxides. Typically, temperatures are
controlled by limiting the amount of material charged to the furnace.
Design Considerations for Municipal-Waste
Poor combustor design can prevent stable, optimal
combustion conditions. Sizing a furnace to match the quantity of waste fed to
the incinerator is important with respect to temperature, turbulence, and time.
Newer grate systems are designed to agitate the waste
in various ways, causing it to be broken into smaller pieces as combustion
proceeds. This process permits exposure of a larger surface area of waste to
air and high temperatures, assisting complete combustion by preventing unburnt
material from simply being transported through on the grate.
For complete combustion to occur, air must be injected
into the furnace in at least two locations: under the grate that carries
burning waste (primary or underfire air) and above the grate to mix additional
oxygen with the combustion gases (secondary or over-fire air). In such advanced
systems, primary air is injected into the drying, burning, and burnout zones of
the grate, with a separate system for secondary air. Control may be effected by
manual or automatic adjustments to dampers. The temperature and oxygen needs of
the furnace can be controlled by adjusting the quantity of primary and
secondary air entering the furnace.
and Bull Noses
To achieve complete
combustion, gases produced must remain in the high-temperature zone of the
furnace for a minimal residence time, usually 1-2 seconds. Achieving that
residence time is usually accomplished by designing the furnace to retard the
upward flow of gases. Arches, which are structures above the burning and
burnout zones, are used to prolong the stay of combustion gases above the grate
area. Bull noses are protrusions that are built into the furnace walls, usually
near the point of injection of over-fire air, to upset the normal upward flow
of the heated gases volatilizing from the burning waste. The induced gas
redirection retards the movement of the combustion gases out of the furnace and
promotes mixing with air.
recirculation systems are used to recycle into the furnace relatively cool flue
gas that contains combustion products and an oxygen concentration lower than
air. The process is used to lower nitrogen oxide formation by limiting the
flame temperature and by slightly diluting the flame oxygen concentration.
particularly municipal solid waste, is heterogeneous, and its components, or
even the whole waste stream, may vary in combustibility. Maintenance of
temperature can be aided by auxiliary burners that are typically set to come on
automatically when the furnace temperature falls below a predetermined point.
The auxiliary burners are fed fossil fuels and are particularly intended to be
used during system startup, shutdown, and upsets.
Many variables that
affect smokeless incinerator operations are controlled by operators. Poor
operator control either of the furnace (by permitting temperature or oxygen
concentration to decrease) or of the stoking operation can cause reduced
combustion efficiency. In most incinerators, mixing and charging of waste into
the incinerator, grate speed, over-fire and under-fire air-injection rates, and
selection of the temperature set point for the auxiliary burner are entirely or
partially controlled by plant personnel.
In addition, the
extent of emission control achieved by post-combustion depends on how the
devices are operated. Suboptimal operation can be caused by poorly trained or
inattentive operators, faulty procedures, and equipment failure. Operators must
be attentive to the flow rate of waste into the incinerator and furnace
operation so as to allow for effective function.
Although some of the
most-modern incineration equipment has been automated, there will always be a
need for operators to deal with unexpected situations. In addition, automated
equipment requires calibration and maintenance, and combustor parts can wear
out or malfunction.
Examples of what can
go wrong include clogged air injection into the incineration chamber, fouled
boiler tubes, a hole in the fabric filters, and a clogged scrubber nozzle.
courses are now required for hazardous-waste workers at remediation sites and
plant facilities. Annual refresher courses are required, as is supplemental
training for supervisory personnel.
Specific Acts and regulations impose federal requirements for
inspection plans and worker-training plans for all facilities that manage
hazardous waste, including combustion facilities. The inspection plans address
facility maintenance, leak inspections, and calibration schedules for
monitoring equipment. Training plans are therefore intended to address
hazardous-material safety and facility operations.
There are now
specific certification guidelines for hazardous waste-incinerator operators.
and Data Collection
enviromental regulations have led to extensive monitoring of key incineration
process conditions, including waste feed rates; feed rates of ash, chlorine,
and toxic metals (determined by sampling and analysis of the waste stream);
combustion temperatures; gas velocity (or gas residence time);
facility-specific air-pollution control-system operating measures; and
stack-gas of varying concentrations.
collect and record process data, automatically control such process conditions
as combustion and automatically cut off waste feeds if operating conditions
stray outside limits set by permits. For example, a low combustion temperature
or high stack-gas CO concentration might initiate an automatic waste-feed
regulations for hazardous-waste incinerators require continuous monitoring of
important air-pollution control-system operating conditions.
Additional factors to be considered;
Air Pollution Control
Gas- Temperature Reduction
Carbon Adsorption and Other
Dioxin and Mercury Removal Techniques
Dioxins & Furans
Ash & Other residues
Liquid waste may not be able
to be processed unless mixed with sand or soil.
Heavy metals may remain in
the ash; which would in turn introduce additional disposal costs
Capital and operating costs
are high and may not be economical for small job sizes
Examples of established products;
Ecogei manufactures and markets specialized”no fuel
co-friendly eincinerators”and “smokeless eco-friendly incinerators” of various
kind and capacities from 01kg to 100ton without usage of any kind fuel for
treating and incinerating hazardous and non-hazardous dry and wet wastes of any
kind, meeting rules, regulations, guidelines, requirement and criteria of
respective departments of respective states globally. ECO Global Engineering
Incorporation (ECO-GEI) offers technologies for onside treatment, digestion and
composting of all food waste/organic waste materials of any kind either crystal
clear water or compost or commercially viable commodities such as granular
fertiliser, animal feed and pure energy or high quality fertilizer or burn into
3% ashes(without smoke,fumes, and emission of solid particles and toxic gases)
using various ranges of ultramodern Digesters and Incinerators made with highly
sophisticated technologies with 100% environmentally friendly and without any
kind of atmospheric pollution.
ENGINEERING CO. LTD
The Matsushita Seiko Engineering Company has been
engaged in the stabilization, reduction in size and recycling of industrial waste
materials. As such, the company has developed a compact smokeless incinerator
specifically for waste plastic and garbage.
This system is;
Easily installed (Shop assembled and instant test
No supply fuel required
Incineration technology and practice can be
implemented under conditions that meet currently applicable and proposed
emissions limits and other environmental regulatory constraints.
Emissions from incineration facilities are
reduced by modifying operating characteristics—such as furnace
temperature, air-injection rate, flue-gas temperature, reagent type, and
injection rate, and by selecting optimal combustor designs and
Use and continued calibration and maintenance
of continuous monitors of emissions and process characteristics provide
real-time feedback and facilitate maintenance of optimal operating
conditions at all times by incineration operators.
Emissions from incineration facilities can be
reduced by choosing advanced combustion designs and emission-control
technologies for the pollutant of concern and by having well-trained and
certified employees who can help to ensure that the combustor is operated
to maximize combustion efficiency and that the emission control devices
are operated to optimize conditions for pollutant capture or neutralization.
Government agencies should encourage the
development and adoption of continuous-emission-monitoring technology.
These data should be made easily available to the public routinely.
Experiences of other countries should be considered. Continuous emission
monitoring of particulate matter and other pollutants of concern from
incineration processes, such as mercury, should be implemented when
practical and reliable techniques are available.
Consideration should be given to establishing
a certification procedure for municipal solid-waste incinerator
control-room operators. Certification standards for qualification of
resource recovery operators, medical-waste incinerator operators, and
hazardous-waste incinerator operators have already been developed. Renewal
of certification should include retesting on new techniques, practices,
Government agencies should gather and
disseminate information on the effects on emissions and ash as a result of
various operating conditions, such as furnace and downstream flue-gas
temperatures, reagent types and injection rates, and air-injection
adjustments. Such guidance should show how specific emissions and ash characteristics
are affected by modifying these process conditions.
Emissions and facility-specific data should be
linked to better characterize the contributions to environmental
concentrations for health-effects assessments.