small capacity incinerators

1    Basic Plant Design    An approved plant must have four distinct sections that demonstrate three principles of Turbulence, Residence Time and Temperature are inbuilt in the plant design .The regulated sections may include but not limited to:

Overall plant layout.
Feed chamber/ charging
Primary Combustion Chamber.
Secondary Combustion Chamber.
Particulate Scrubbers
Acid Gas Scrubbers
The stack/ chimney.
2    Feeding And Charging    Controlled hygienic, mechanical or automatic feeding methods have to be used which will not influence the air temperature in the primary and secondary chambers of the incinerator negatively.

No waste is to be fed into the incinerator:

1.    Until the minimum temperatures have been reached.
2.    If the minimum combustion temperatures are not maintained.
3.    Whenever the previous charge has not been completely combusted in the case of batch feeding.

4.    Until such time as the addition of more waste will not cause the design parameters of the incinerator to be exceeded.

3    Primary Combustion Chamber    The primary combustion chamber must:

1.    Be accepted as the primary combustion zone.
2.    Be equipped with a burner/s burning gas/fuel or low sulphur liquid fuels. Other combustion methods will be judged on merits.

3.    Ensure primary air supply is controlled efficiently
4.    Ensure minimum exit temperature is not less than 850oC

4    Secondary Combustion Chamber (Afterburner).    The secondary combustion chamber must:

1.    Be accepted as secondary combustion zone.
2.    Be fitted with secondary burner/s burning gas or low sulphur liquid fuel or any suitable fuel.

3.    Ensure secondary air supply is controlled efficiently.
4.    Ensure flame contact with all gases is achieved.
5.    Ensure residence time is not less than two (2) seconds.
6.    Ensure the gas temperature as measured against the inside wall in the secondary chamber & not in the flame zone, is not less than 1100oC.

7.    Ensure the oxygen content of the emitted gases is not less than 11%.
8.    Ensure both primary and the combustion temperatures are maintained until all waste has been completely combusted

5    Particulate Removers    A mechanical particulate collector must be incorporated after secondary combustion chamber for removal of particulate pollutants entrained in the flue gas stream. The particulate collectors may include any of the following or a combination thereof:

Cyclone separator
Electrostatic precipitators
Fabric filters
6    Chimney / Stack    1.    The chimney should have a minimum height of 10 meters above ground level and clear the highest point of the building by not less than 3 meters for all roofs. The topography and height of adjacent buildings within 50 meters radius should be taken into account.

2.    If possible the chimney should be visible to the operator from the feeding area.
3.    The addition of dilution air after combustion in order to achieve the requirement of these guidelines is unacceptable.

4.    The minimum exit velocity should be 10 m/s and at least twice the surrounding wind speed (Efflux velocity = wind speed x 2) whichever is higher to ensure no down washing of exiting gases.

5.    Point for the measurement of emissions shall be provided.

7    Instrumentation    Instrument for determining the inside wall temperature and not burner flame temperature must be provided for both primary and secondary chambers.

2.    An audible and visible alarm must be installed to warn the operator when the secondary temperature drops to below the required temperature.

3.    In addition to the above the following instruments may also be required.
A carbon monoxide and/or oxygen meter/recorder
A smoke density meter/recorder
A gas flow meter/recorder
A solid particulate meter/recorder
Any other instrument or measurement that may be considered necessary

8    Location / Siting    1.    Must be sited in accordance with the relevant local municipal authority planning scheme, the topography of the area and be compatible with premises in the neighborhood,

2.    Must be housed in a suitably ventilated room.

9    Emission Limits    1.    Combustion efficiency:

Combustion efficiency (CE) shall be at least 99.00%
The Combustion efficiency is computed as follows;

C.E=             % CO2           x 100
% CO2 + CO

2.    The temperature of the primary chamber shall be 800 ± 50o C

3.    The secondary chamber  gas residence time shall be at least 1 (one) second at 1050 ± 50o C, with 3% Oxygen in the stack gas.

4    Opacity of the smoke must not exceed 20% Viewed from 50 meters with naked eyes
5.    All the emission to the air other than steam or water vapour must be odourless and free from mist, fume and droplets.

6.    The Authority may require that the certificate holder have tests carried out by an accredited institution to determine stack and/or ground level concentrations of the following substances.

Cadmium and compounds as     Cd
Mercury                                      Hg
Thallium                                     Tl

Chromium                                  Cr
Beryllium                                    Be
Arsenic                                       As
Antimony                                    Sb
Barium                                        Ba
Lead                                            Pb
Silver                                          Ag
Cobalt                                         Co
Copper                                        Cu
Manganese                                  Mn
Tin                                               Sn
Vanadium                                     V
Nickel                                           Ni
Hydrochloric                                HCL
Hydrofluoric acid                         HF
Sulphur dioxide                           S02

7.    A 99.99% destruction and removal efficiency (DRE) for each principal organic hazardous constituent (POHC) in the waste feed where:

DRE = [(Win – Wout)/Win]*100
Where: Win = mass feed rate of the POHC in the waste stream fed to incinerator, and
Wout = mass emission rate of POHC in the stack prior to the release to the atmosphere.

8.    The average dioxin and furan concentration in the emissions should not exceed 80ng/m3 total dioxins and furans if measured for a period of 6 to 16 hours.

All pollutant concentrations must be expressed at Oo C and 1.013 x 10 5 N/m2, dry gas and 11% oxygen correction.

Oxygen correction is computed as:

Es =     21 – Os    x EM
21 – OM

Where:    Es    = Calculated emission concentration at the standard percentage oxygen concentration
EM    = Measured emission concentration
Os    = Standard oxygen concentration
OM    = measured oxygen concentration

10    Operation    1.    Materials destined for incineration should be of known origin and composition and must be only incinerated in a furnace that is registered for the particular type of waste.

2.    A record must be kept of the quantity, type and origin of the waste to be incinerated.
3.    The incinerator must be preheated to working temperature before charging any waste.
4.    The incinerator must not be overcharged.
5.    The incinerator must be in good working order at all times and must not be used if any component fails. Any malfunction should be recorded in a log book and reported to the relevant authority.

6.    The incinerator operator and all relevant staff must be trained to the satisfaction of the relevant control authority.

11    Housekeeping    The site where the incinerator is built must:

1.    Have running water.
2.    Have a solid floor.
3.     Have lighting if 24hrs operation
4.    Have fly ash containerization and storage before disposal.

12    Health & Safety (Protective Gear)    1.    Staff handling waste must be well trained on safe handling of hazardous wastes
2.     Staff must be provided with appropriate  protective gear such as, gas mask, aprons, gumboots, helmets, gloves, goggles.

3.     Caution and Warning signs must be provided.
4.     Fire fighting equipment must be provided
5.     There should be no smoking or eating on the site.