Principles of Combustion

A type of incinerator that provides for a controlled combustion process with the purpose of reducing human remains to CO2, water vapor, and small non-combustible residues

Cremators

For our purposes, this is the application of combustion in the cremation process

Incineration

Flame based cremation

Combustion

Combustion is more than the simple act of burning, a highly complex chemical process requiring 3 things in the right portions:

- Oxygen

- Heat

- Fuel

_______ is the resulting chemical reaction of those 3 elements and can't start or continue if any one of them aren't present

Fire

Heat is a form of what?

Energy

Oxygen is the most common:

Oxidizer

Fuel is most commonly:

Hydrocarbon based

Fire occurs when:

A combustible material, in combination with a sufficient quantity of oxygen, is exposed to an external ignition source above the flash point for the fuel and oxidizer mix

Molecules rearrange themselves, either releasing or absorbing energy in a process known as:

Oxidation

To sustain a flame:

A chemical reaction must be able to maintain a rate of rapid oxidation that produces a self-sustaining, exothermic chemiical chain reaction

A rapid oxidation process in which hydrocarbons react with oxygen to release a great deal of heat and light

Incineration

- Occurs when heat doesn't dissipate faster than it is created

- Complete destruction of organic matter to form harmless gasses

- Prevention of the release of harmful materials into the atmosphere

Combustion

Simple combustion process:

Fuel + Oxygen = Carbon Dioxide + Water

The theoretical point where the ratio of fuel to oxygen results in complete combustion, when all the carbon in the fuel forms CO2, and all the hydrogen forms H2O

Stoichiometric Combustion or Perfect Combustion

Incomplete combustion occurs when:

Complete combustion of a combustible material doesn't happen

What is the cause of one atom of carbon uniting with only one atom of oxygen creating carbon monoxide (CO) rather than carbon dioxide (CO2)

Lack of oxygen

To achieve complete combustion:

It is vital to control the amounts of air introduced to the combustion process to ensure the burning of all fuel

The amount of air necessary to make certain all energy is retrieved

Excess air

Adjustment of the _________ so that the proper level of excess air is present is key

Combustion process

Cremator operators make adjustments based on:

- Type of fuel supply (Ex: fuel + cremation container + remains)

- Changes in atmospheric pressure

- Time of day

We must understand that combustion spreads from _______________ to _______________

Ignition source; adjacent layer of gas mixture

Each point of _________ serves as ignition for the next one

Burning layer

When the total heat energies of the __________ and the total heat energies of the _____________ reach equilibrium, combustion ends

Reactants; products

The substances that take part in and undergo change during a chemical reaction

Reactants

Incineration is a:

Controlled combustion process

A chemical reaction of combustible waste materials with air for the primary purpose of destruction and reduction in volume and weight

Incineration

Drying of combustible material to drive off moisture, volatilization of the vapors and gases which occur as the temperature of the material rises, combustion of the charge, and burnout of the solids

Primary Incineration

Combustion of vapors, gases, and particulates driven off during the primary process

Secondary Incineration

In 1968, the ________________________ defined and classified varying incinerator standards and the types of waste produced by them

Incinerator Institute of America

Crematory incinerators are defined as:

Class VI Crematory and Pathological Incinerators Suitable for Type 4 waste

"Pathological. 100% human and animal tissue, organs, and solid organize wastes from hospitals, laboratories, animal pounds, farms, abattoirs, etc.; containing up to 85% moisture by weight. Average heat value 1,000-2,000 BTU/lb."

Type 4 Waste

Cremation of human pathological waste is _____________ in most states

Permissible

Crematories that accept pathological waste for cremation must consider:

The legalities of engaging in such business practices

Materials some states will not cremate:

- Municipal solid waste

- Medical/infectious waste (other than pathological waste)

- Radioactive waste

- Hazardous waste

- Fiberglass and plastic

- Narcotics

A multiple-chambered retort that is specifically designed for the incineration of human remains

Cremator

Two basic multiple-chamber designs:

- In-line hearth

- Retort hearth

Combustion gases flow vertically

In-line hearth

- Flow of combustion gases is directed sideways through a secondary chamber adjacent to the primary combustion chamber

- The most efficient design for cases weighing less than 750 lbs

Retort hearth

Placement of the case or "charge" into the:

Primary combustion/incineration chamber

Ignition of the __________ to bring the secondary chamber up to the target temperature

Afterburner

Ignition of the ____________ once target temperature is achieved

Primary burner

Excess air is added through the:

Flame port

Excess air is mixed with ___________ in the secondary chamber, where they get ignited by a burner there

Volatile contentes

Gasses exit the _____________ through the _____________

Secondary chamber; Cremator stack

When all waste is driven off or consumed, the ________ shuts off, followed by the ____________ after a set amount of time

Primary burner; afterburner

The three major factors affecting the efficiency of a cremation:

- Time

- Temperature

- Turbulence

It is essential that the products of combustion be given enough ____________ in the afterburner chamber/primary cremation chamber to be consumed so they aren't released into the __________

Retention time; atmosphere

Proper temperature range is between:

1,400 and 1,800

Some states require the secondary chamber to remain at __________ during operation to ensure total incineration of the cremation container or any other products of combustion

1,800 F

Temperatures above _____________ will cause products of combustion to move through the afterchamber too quickly, resulting in visible emissions

1,800 F

- Increases combustion efficiency

- Created in the cremator's exhaust system by having the gasses change directions through perforated walls and battle systmes

- Aids in the mixture of gases, driving off and consuming any products of combustion before release into the atmosphere

Turbulence

The average human body is between ________ moisture

60-90%

Retorts are designed with a fixed hearth with a raised edge at the door to prevent:

Liquids from spilling during charging

Average heat value as fired of a human body is:

800-3,600 BTU/lb

The body of a healthy, lean adult male is composed of about ______ water

62%

The body of a healthy, lean adult male is composed of about ________ fat

16%

The body of a healthy, lean adult male is composed of about _________ minerals

6%

The body of a healthy, lean adult male is composed of about less than __________ carbohydrates

1%

Healthy, lean adult females carry about _______ fat and slightly fewer other chemical components

22%

Chemical composition of cremated human remains of oxygen:

61%

Chemical composition of cremated human remains of carbon:

23%

Chemical composition of cremated human remains of hydrogen:

10%

Chemical composition of cremated human remains of nitrogen:

3%

Chemical composition of cremated human remains of calcium:

1.4%

Chemical composition of cremated human remains of phosphorus:

1.1%

Chemical composition of cremated human remains of potassium:

0.2%

Chemical composition of cremated human remains of sulfur:

0.2%

Chemical composition of cremated human remains of sodium:

0.14%

Chemical composition of cremated human remains of chlorine:

0.12%

Chemical composition of cremated human remains of magnesium, silicon, iron, fluorine, and zinc:

0.03-0.003%

Major constituents of air emissions from cremation include:

- Organic compounds

- Nitrogen oxides

- Sulfur dioxides

- Carbon monoxide

- Particulate matter

Typical PM standard for crematories is not to exceed _______ grains per dry standard cubic foot of flue gas

0.08

100% of the background is visible through the exhaust and vice versa

Zero percent opacity

- Devices used to trap suspended particles by direct contract with a spray of water or another liquid

- Sometimes called flue gas washers

- Washes fly ash, odorous compounds, and other objectionable materials out of the airstream as they're carried along by droplets in the spray

- Not commonly used in the U.S. on cremation equipment due to high costs

Wet Scrubbers

- Removes suspended particulates using an assembly of fabric-filter bags

- Dust-laden air is blown upward by fans that trap the particulates inside

- Offers high resistance to air flow, leading to substantial energy use to the system

- Uncommon usage due to high costs

Baghouse/ Fabric Filtration