4-24 Pyrolysis

You can find more information on our web, so please take a look.

Description:

Figure 4-24: Typical Pyrolysis Process Pyrolysis is formally defined as chemical decomposition induced in organic materials by heat in the absence of oxygen. In practice, it is not possible to achieve a completely oxygen-free atmosphere; actual pyrolytic systems are operated with less than stoichiometric quantities of oxygen. Because some oxygen will be present in any pyrolytic system, nominal oxidation will occur. If volatile or semivolatile materials are present in the waste, thermal desorption will also occur.

Pyrolysis transforms hazardous organic materials into gaseous components, small quantities of liquid, and a solid residue (coke) containing fixed carbon and ash. Pyrolysis of organic materials produces combustible gases, including carbon monoxide, hydrogen and methane, and other hydrocarbons. If the off-gases are cooled, liquids condense producing an oil/tar residue and contaminated water. Pyrolysis typically occurs under pressure and at operating temperatures above 430 °C (800 °F). The pyrolysis gases require further treatment. The off-gases may be treated in a secondary combustion chamber, flared, and partially condensed. Particulate removal equipment such as fabric filters or wet scrubbers are also required.

Conventional thermal treatment methods, such as rotary kiln, rotary hearth furnace, or fluidized bed furnace, are used for waste pyrolysis. Kilns or furnaces used for pyrolysis would be physically similar to the equipment described in Section 4.23 "Incineration", but would operate at lower temperature and with less air supply than would be required for combustion. Molten salt process may also be used for waste pyrolysis. These processes are described in the following sections:

Rotary Kiln

The rotary kiln is a refractory-lined, slightly-inclined, rotating cylinder that serves as a heating chamber.

Sihai Energy Product Page

Fluidized Bed Furnace

The circulating fluidized bed uses high-velocity air to circulate and suspend the waste particles in a heating loop and operates at temperatures up to 430 °C (800 °F).

Molten Salt Destruction

Molten-salt destruction is another type of pyrolysis. In molten-salt destruction, a molten salt incinerator uses a molten, turbulent bed of salt, such as sodium carbonate, as a heat transfer and reaction/scrubbing meduim to destroy hazardous materials. Shredded solid waste is injected with air under the surface of the molten salt. Hot gases composed primarily of carbon dioxide, stream, and unreacted air components rise through the molten salt bath, pass throught a secondary reaction zone, and through an off gas cleanup system before discharging to the atmosphere. Other pyrolysis by-products react with the alkaline molten salt to form inorganic products that are retained in the melt. Spent molten salt containing ash is tapped from the reactor, cooled and placed in a landfill.

Pyrolysis is an emerging technology. Although the basic concepts of the process have been validated, the performance data for an emerging technology have not been evaluated according to methods approved by EPA and adhering to EPA quality assurance/quality control standards. Performance data are currently available only for vendors. Also, existing data are limited in scope and quantity/quality and are frequently of a proprietary nature.

The company is the world’s best Waste Pyrolysis Plant supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.