Rotary Kilns for Pollution Control

2 February 2017   Anti-Pollution

Hazardous waste incineration with Rotary Kilns

HiTempTech has developed and built many anti-pollution systems which burn hazardous materials at a high temperature and end up with environmentally friendly gases.  One of the anti-pollution systems we build is a rotary kiln.  Please look at our videos on the Waste to Energy Videos page.
Rotary Kiln
A rotary kiln incinerator is considered a pyroprocessing device, or a device that uses high temperatures to chemically or physically change materials. This device rotates different materials, typically hazardous waste, in a series of drums at extremely high temperatures in order to destroy them safely and with as little environmental impact as possible. Rotary kiln incinerators are used by local municipalities and industrial plants to process mixed industrial and hazardous wastes that include a combination of solid and liquid waste and sludge. Some of the advantages of using a rotary kiln incinerator are its flexible and robust design which burns a wide range of waste, including hazardous waste, medical waste, infectious waste, chemical waste and pesticides, sludge waste, industrial waste, etc., and its high efficiency in destruction and low environmental impact via emissions.

Directly heated kilns heat materials in the rotating tube by an open flame via a hot gas stream that flows throughout the interior, attaining high temperatures ranging from and 600°C to 1,550°C speeds. This direct contact between the material and process gas efficiently process the material, and combustion can occur in a combustion chamber to avoid direct flame radiation to the materials.

It has 2 chambers: a primary chamber and a secondary chamber.

Rotary kiln incinerators are manufactured with a rotating combustion chamber to keep waste moving, which allows it to vaporize for easier burning. The primary ignition or combustion chamber is a rotating chamber that uses extremely high temperatures to burn off contaminated materials such as sludge and soil from industrial sites. Ash from the primary chamber settles to the bottom, and as the chamber rotates, the ash and other non-combustibles exit through a slot at the edge of a kiln where they are collected into an ash receptacle. These are continuously discharged and collected during the incineration process. The secondary chamber, or afterburner, operates at a higher temperature and consumes and the chemical vapors, smoke, and particulate leftover from the primary chamber.

In addition to the combustion chambers, rotary kiln incinerators can use an energy recovery system to collect energy outputs (electric, heat, steam, etc) in order to save money and use for other purposes on the facility.
Rotary Kiln

Lastly, a rotary kiln incinerator must treat flue gas that is produced as a result of the other chemical processes. Flue gas, named as such because it exits the plant via a “flue,” or a pipe or channel, refers to the combustion exhaust exiting the kiln that can consist of chlorine, sulfur, nitrogen, water vapor, and a number of other pollutants. The flue gas must be treated with a series of chemical processes and scrubbers to remove pollutants.

The rotary kiln incinerator is generally used to incinerate hazardous materials over other incinerators such as cement kilns because of the decreased environmental risk to global warming, eutrophication, human toxicity and acidification. According to a 2009 study by Vermeulen et al., and because of its ability to incinerate caloric waste and fossil fuels alike, the environmental impact is “considerably smaller due to the effectiveness of the flue gas cleaning of the rotary kiln and the avoided emissions due to steam and electricity generation.”

HiTempTech has many years of experience building rotary kilns all over the world and in the United States, including the Fort Knox Army Base.  Please look on our downloads page to see examples of rotary kilns we built in 2016 and to get a quotation.